diff --git a/demo_test/vendor/google.golang.org/protobuf/encoding/prototext/decode.go b/demo_test/vendor/google.golang.org/protobuf/encoding/prototext/decode.go
new file mode 100644
index 0000000..cde2c20
--- /dev/null
+++ b/demo_test/vendor/google.golang.org/protobuf/encoding/prototext/decode.go
@@ -0,0 +1,788 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package prototext
+
+import (
+	"fmt"
+	"strings"
+	"unicode/utf8"
+
+	"google.golang.org/protobuf/internal/encoding/messageset"
+	"google.golang.org/protobuf/internal/encoding/text"
+	"google.golang.org/protobuf/internal/errors"
+	"google.golang.org/protobuf/internal/fieldnum"
+	"google.golang.org/protobuf/internal/flags"
+	"google.golang.org/protobuf/internal/pragma"
+	"google.golang.org/protobuf/internal/set"
+	"google.golang.org/protobuf/proto"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
+)
+
+// Unmarshal reads the given []byte into the given proto.Message.
+func Unmarshal(b []byte, m proto.Message) error {
+	return UnmarshalOptions{}.Unmarshal(b, m)
+}
+
+// UnmarshalOptions is a configurable textproto format unmarshaler.
+type UnmarshalOptions struct {
+	pragma.NoUnkeyedLiterals
+
+	// AllowPartial accepts input for messages that will result in missing
+	// required fields. If AllowPartial is false (the default), Unmarshal will
+	// return error if there are any missing required fields.
+	AllowPartial bool
+
+	// DiscardUnknown specifies whether to ignore unknown fields when parsing.
+	// An unknown field is any field whose field name or field number does not
+	// resolve to any known or extension field in the message.
+	// By default, unmarshal rejects unknown fields as an error.
+	DiscardUnknown bool
+
+	// Resolver is used for looking up types when unmarshaling
+	// google.protobuf.Any messages or extension fields.
+	// If nil, this defaults to using protoregistry.GlobalTypes.
+	Resolver interface {
+		protoregistry.MessageTypeResolver
+		protoregistry.ExtensionTypeResolver
+	}
+}
+
+// Unmarshal reads the given []byte and populates the given proto.Message using options in
+// UnmarshalOptions object.
+func (o UnmarshalOptions) Unmarshal(b []byte, m proto.Message) error {
+	proto.Reset(m)
+
+	if o.Resolver == nil {
+		o.Resolver = protoregistry.GlobalTypes
+	}
+
+	dec := decoder{text.NewDecoder(b), o}
+	if err := dec.unmarshalMessage(m.ProtoReflect(), false); err != nil {
+		return err
+	}
+	if o.AllowPartial {
+		return nil
+	}
+	return proto.CheckInitialized(m)
+}
+
+type decoder struct {
+	*text.Decoder
+	opts UnmarshalOptions
+}
+
+// newError returns an error object with position info.
+func (d decoder) newError(pos int, f string, x ...interface{}) error {
+	line, column := d.Position(pos)
+	head := fmt.Sprintf("(line %d:%d): ", line, column)
+	return errors.New(head+f, x...)
+}
+
+// unexpectedTokenError returns a syntax error for the given unexpected token.
+func (d decoder) unexpectedTokenError(tok text.Token) error {
+	return d.syntaxError(tok.Pos(), "unexpected token: %s", tok.RawString())
+}
+
+// syntaxError returns a syntax error for given position.
+func (d decoder) syntaxError(pos int, f string, x ...interface{}) error {
+	line, column := d.Position(pos)
+	head := fmt.Sprintf("syntax error (line %d:%d): ", line, column)
+	return errors.New(head+f, x...)
+}
+
+// unmarshalMessage unmarshals into the given protoreflect.Message.
+func (d decoder) unmarshalMessage(m pref.Message, checkDelims bool) error {
+	messageDesc := m.Descriptor()
+	if !flags.ProtoLegacy && messageset.IsMessageSet(messageDesc) {
+		return errors.New("no support for proto1 MessageSets")
+	}
+
+	if messageDesc.FullName() == "google.protobuf.Any" {
+		return d.unmarshalAny(m, checkDelims)
+	}
+
+	if checkDelims {
+		tok, err := d.Read()
+		if err != nil {
+			return err
+		}
+
+		if tok.Kind() != text.MessageOpen {
+			return d.unexpectedTokenError(tok)
+		}
+	}
+
+	var seenNums set.Ints
+	var seenOneofs set.Ints
+	fieldDescs := messageDesc.Fields()
+
+	for {
+		// Read field name.
+		tok, err := d.Read()
+		if err != nil {
+			return err
+		}
+		switch typ := tok.Kind(); typ {
+		case text.Name:
+			// Continue below.
+		case text.EOF:
+			if checkDelims {
+				return text.ErrUnexpectedEOF
+			}
+			return nil
+		default:
+			if checkDelims && typ == text.MessageClose {
+				return nil
+			}
+			return d.unexpectedTokenError(tok)
+		}
+
+		// Resolve the field descriptor.
+		var name pref.Name
+		var fd pref.FieldDescriptor
+		var xt pref.ExtensionType
+		var xtErr error
+		var isFieldNumberName bool
+
+		switch tok.NameKind() {
+		case text.IdentName:
+			name = pref.Name(tok.IdentName())
+			fd = fieldDescs.ByName(name)
+			if fd == nil {
+				// The proto name of a group field is in all lowercase,
+				// while the textproto field name is the group message name.
+				gd := fieldDescs.ByName(pref.Name(strings.ToLower(string(name))))
+				if gd != nil && gd.Kind() == pref.GroupKind && gd.Message().Name() == name {
+					fd = gd
+				}
+			} else if fd.Kind() == pref.GroupKind && fd.Message().Name() != name {
+				fd = nil // reset since field name is actually the message name
+			}
+
+		case text.TypeName:
+			// Handle extensions only. This code path is not for Any.
+			xt, xtErr = d.findExtension(pref.FullName(tok.TypeName()))
+
+		case text.FieldNumber:
+			isFieldNumberName = true
+			num := pref.FieldNumber(tok.FieldNumber())
+			if !num.IsValid() {
+				return d.newError(tok.Pos(), "invalid field number: %d", num)
+			}
+			fd = fieldDescs.ByNumber(num)
+			if fd == nil {
+				xt, xtErr = d.opts.Resolver.FindExtensionByNumber(messageDesc.FullName(), num)
+			}
+		}
+
+		if xt != nil {
+			fd = xt.TypeDescriptor()
+			if !messageDesc.ExtensionRanges().Has(fd.Number()) || fd.ContainingMessage().FullName() != messageDesc.FullName() {
+				return d.newError(tok.Pos(), "message %v cannot be extended by %v", messageDesc.FullName(), fd.FullName())
+			}
+		} else if xtErr != nil && xtErr != protoregistry.NotFound {
+			return d.newError(tok.Pos(), "unable to resolve [%s]: %v", tok.RawString(), xtErr)
+		}
+		if flags.ProtoLegacy {
+			if fd != nil && fd.IsWeak() && fd.Message().IsPlaceholder() {
+				fd = nil // reset since the weak reference is not linked in
+			}
+		}
+
+		// Handle unknown fields.
+		if fd == nil {
+			if d.opts.DiscardUnknown || messageDesc.ReservedNames().Has(name) {
+				d.skipValue()
+				continue
+			}
+			return d.newError(tok.Pos(), "unknown field: %v", tok.RawString())
+		}
+
+		// Handle fields identified by field number.
+		if isFieldNumberName {
+			// TODO: Add an option to permit parsing field numbers.
+			//
+			// This requires careful thought as the MarshalOptions.EmitUnknown
+			// option allows formatting unknown fields as the field number and the
+			// best-effort textual representation of the field value.  In that case,
+			// it may not be possible to unmarshal the value from a parser that does
+			// have information about the unknown field.
+			return d.newError(tok.Pos(), "cannot specify field by number: %v", tok.RawString())
+		}
+
+		switch {
+		case fd.IsList():
+			kind := fd.Kind()
+			if kind != pref.MessageKind && kind != pref.GroupKind && !tok.HasSeparator() {
+				return d.syntaxError(tok.Pos(), "missing field separator :")
+			}
+
+			list := m.Mutable(fd).List()
+			if err := d.unmarshalList(fd, list); err != nil {
+				return err
+			}
+
+		case fd.IsMap():
+			mmap := m.Mutable(fd).Map()
+			if err := d.unmarshalMap(fd, mmap); err != nil {
+				return err
+			}
+
+		default:
+			kind := fd.Kind()
+			if kind != pref.MessageKind && kind != pref.GroupKind && !tok.HasSeparator() {
+				return d.syntaxError(tok.Pos(), "missing field separator :")
+			}
+
+			// If field is a oneof, check if it has already been set.
+			if od := fd.ContainingOneof(); od != nil {
+				idx := uint64(od.Index())
+				if seenOneofs.Has(idx) {
+					return d.newError(tok.Pos(), "error parsing %q, oneof %v is already set", tok.RawString(), od.FullName())
+				}
+				seenOneofs.Set(idx)
+			}
+
+			num := uint64(fd.Number())
+			if seenNums.Has(num) {
+				return d.newError(tok.Pos(), "non-repeated field %q is repeated", tok.RawString())
+			}
+
+			if err := d.unmarshalSingular(fd, m); err != nil {
+				return err
+			}
+			seenNums.Set(num)
+		}
+	}
+
+	return nil
+}
+
+// findExtension returns protoreflect.ExtensionType from the Resolver if found.
+func (d decoder) findExtension(xtName pref.FullName) (pref.ExtensionType, error) {
+	xt, err := d.opts.Resolver.FindExtensionByName(xtName)
+	if err == nil {
+		return xt, nil
+	}
+	return messageset.FindMessageSetExtension(d.opts.Resolver, xtName)
+}
+
+// unmarshalSingular unmarshals a non-repeated field value specified by the
+// given FieldDescriptor.
+func (d decoder) unmarshalSingular(fd pref.FieldDescriptor, m pref.Message) error {
+	var val pref.Value
+	var err error
+	switch fd.Kind() {
+	case pref.MessageKind, pref.GroupKind:
+		val = m.NewField(fd)
+		err = d.unmarshalMessage(val.Message(), true)
+	default:
+		val, err = d.unmarshalScalar(fd)
+	}
+	if err == nil {
+		m.Set(fd, val)
+	}
+	return err
+}
+
+// unmarshalScalar unmarshals a scalar/enum protoreflect.Value specified by the
+// given FieldDescriptor.
+func (d decoder) unmarshalScalar(fd pref.FieldDescriptor) (pref.Value, error) {
+	tok, err := d.Read()
+	if err != nil {
+		return pref.Value{}, err
+	}
+
+	if tok.Kind() != text.Scalar {
+		return pref.Value{}, d.unexpectedTokenError(tok)
+	}
+
+	kind := fd.Kind()
+	switch kind {
+	case pref.BoolKind:
+		if b, ok := tok.Bool(); ok {
+			return pref.ValueOfBool(b), nil
+		}
+
+	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
+		if n, ok := tok.Int32(); ok {
+			return pref.ValueOfInt32(n), nil
+		}
+
+	case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
+		if n, ok := tok.Int64(); ok {
+			return pref.ValueOfInt64(n), nil
+		}
+
+	case pref.Uint32Kind, pref.Fixed32Kind:
+		if n, ok := tok.Uint32(); ok {
+			return pref.ValueOfUint32(n), nil
+		}
+
+	case pref.Uint64Kind, pref.Fixed64Kind:
+		if n, ok := tok.Uint64(); ok {
+			return pref.ValueOfUint64(n), nil
+		}
+
+	case pref.FloatKind:
+		if n, ok := tok.Float32(); ok {
+			return pref.ValueOfFloat32(n), nil
+		}
+
+	case pref.DoubleKind:
+		if n, ok := tok.Float64(); ok {
+			return pref.ValueOfFloat64(n), nil
+		}
+
+	case pref.StringKind:
+		if s, ok := tok.String(); ok {
+			if utf8.ValidString(s) {
+				return pref.ValueOfString(s), nil
+			}
+			return pref.Value{}, d.newError(tok.Pos(), "contains invalid UTF-8")
+		}
+
+	case pref.BytesKind:
+		if b, ok := tok.String(); ok {
+			return pref.ValueOfBytes([]byte(b)), nil
+		}
+
+	case pref.EnumKind:
+		if lit, ok := tok.Enum(); ok {
+			// Lookup EnumNumber based on name.
+			if enumVal := fd.Enum().Values().ByName(pref.Name(lit)); enumVal != nil {
+				return pref.ValueOfEnum(enumVal.Number()), nil
+			}
+		}
+		if num, ok := tok.Int32(); ok {
+			return pref.ValueOfEnum(pref.EnumNumber(num)), nil
+		}
+
+	default:
+		panic(fmt.Sprintf("invalid scalar kind %v", kind))
+	}
+
+	return pref.Value{}, d.newError(tok.Pos(), "invalid value for %v type: %v", kind, tok.RawString())
+}
+
+// unmarshalList unmarshals into given protoreflect.List. A list value can
+// either be in [] syntax or simply just a single scalar/message value.
+func (d decoder) unmarshalList(fd pref.FieldDescriptor, list pref.List) error {
+	tok, err := d.Peek()
+	if err != nil {
+		return err
+	}
+
+	switch fd.Kind() {
+	case pref.MessageKind, pref.GroupKind:
+		switch tok.Kind() {
+		case text.ListOpen:
+			d.Read()
+			for {
+				tok, err := d.Peek()
+				if err != nil {
+					return err
+				}
+
+				switch tok.Kind() {
+				case text.ListClose:
+					d.Read()
+					return nil
+				case text.MessageOpen:
+					pval := list.NewElement()
+					if err := d.unmarshalMessage(pval.Message(), true); err != nil {
+						return err
+					}
+					list.Append(pval)
+				default:
+					return d.unexpectedTokenError(tok)
+				}
+			}
+
+		case text.MessageOpen:
+			pval := list.NewElement()
+			if err := d.unmarshalMessage(pval.Message(), true); err != nil {
+				return err
+			}
+			list.Append(pval)
+			return nil
+		}
+
+	default:
+		switch tok.Kind() {
+		case text.ListOpen:
+			d.Read()
+			for {
+				tok, err := d.Peek()
+				if err != nil {
+					return err
+				}
+
+				switch tok.Kind() {
+				case text.ListClose:
+					d.Read()
+					return nil
+				case text.Scalar:
+					pval, err := d.unmarshalScalar(fd)
+					if err != nil {
+						return err
+					}
+					list.Append(pval)
+				default:
+					return d.unexpectedTokenError(tok)
+				}
+			}
+
+		case text.Scalar:
+			pval, err := d.unmarshalScalar(fd)
+			if err != nil {
+				return err
+			}
+			list.Append(pval)
+			return nil
+		}
+	}
+
+	return d.unexpectedTokenError(tok)
+}
+
+// unmarshalMap unmarshals into given protoreflect.Map. A map value is a
+// textproto message containing {key: <kvalue>, value: <mvalue>}.
+func (d decoder) unmarshalMap(fd pref.FieldDescriptor, mmap pref.Map) error {
+	// Determine ahead whether map entry is a scalar type or a message type in
+	// order to call the appropriate unmarshalMapValue func inside
+	// unmarshalMapEntry.
+	var unmarshalMapValue func() (pref.Value, error)
+	switch fd.MapValue().Kind() {
+	case pref.MessageKind, pref.GroupKind:
+		unmarshalMapValue = func() (pref.Value, error) {
+			pval := mmap.NewValue()
+			if err := d.unmarshalMessage(pval.Message(), true); err != nil {
+				return pref.Value{}, err
+			}
+			return pval, nil
+		}
+	default:
+		unmarshalMapValue = func() (pref.Value, error) {
+			return d.unmarshalScalar(fd.MapValue())
+		}
+	}
+
+	tok, err := d.Read()
+	if err != nil {
+		return err
+	}
+	switch tok.Kind() {
+	case text.MessageOpen:
+		return d.unmarshalMapEntry(fd, mmap, unmarshalMapValue)
+
+	case text.ListOpen:
+		for {
+			tok, err := d.Read()
+			if err != nil {
+				return err
+			}
+			switch tok.Kind() {
+			case text.ListClose:
+				return nil
+			case text.MessageOpen:
+				if err := d.unmarshalMapEntry(fd, mmap, unmarshalMapValue); err != nil {
+					return err
+				}
+			default:
+				return d.unexpectedTokenError(tok)
+			}
+		}
+
+	default:
+		return d.unexpectedTokenError(tok)
+	}
+}
+
+// unmarshalMap unmarshals into given protoreflect.Map. A map value is a
+// textproto message containing {key: <kvalue>, value: <mvalue>}.
+func (d decoder) unmarshalMapEntry(fd pref.FieldDescriptor, mmap pref.Map, unmarshalMapValue func() (pref.Value, error)) error {
+	var key pref.MapKey
+	var pval pref.Value
+Loop:
+	for {
+		// Read field name.
+		tok, err := d.Read()
+		if err != nil {
+			return err
+		}
+		switch tok.Kind() {
+		case text.Name:
+			if tok.NameKind() != text.IdentName {
+				if !d.opts.DiscardUnknown {
+					return d.newError(tok.Pos(), "unknown map entry field %q", tok.RawString())
+				}
+				d.skipValue()
+				continue Loop
+			}
+			// Continue below.
+		case text.MessageClose:
+			break Loop
+		default:
+			return d.unexpectedTokenError(tok)
+		}
+
+		name := tok.IdentName()
+		switch name {
+		case "key":
+			if !tok.HasSeparator() {
+				return d.syntaxError(tok.Pos(), "missing field separator :")
+			}
+			if key.IsValid() {
+				return d.newError(tok.Pos(), `map entry "key" cannot be repeated`)
+			}
+			val, err := d.unmarshalScalar(fd.MapKey())
+			if err != nil {
+				return err
+			}
+			key = val.MapKey()
+
+		case "value":
+			if kind := fd.MapValue().Kind(); (kind != pref.MessageKind) && (kind != pref.GroupKind) {
+				if !tok.HasSeparator() {
+					return d.syntaxError(tok.Pos(), "missing field separator :")
+				}
+			}
+			if pval.IsValid() {
+				return d.newError(tok.Pos(), `map entry "value" cannot be repeated`)
+			}
+			pval, err = unmarshalMapValue()
+			if err != nil {
+				return err
+			}
+
+		default:
+			if !d.opts.DiscardUnknown {
+				return d.newError(tok.Pos(), "unknown map entry field %q", name)
+			}
+			d.skipValue()
+		}
+	}
+
+	if !key.IsValid() {
+		key = fd.MapKey().Default().MapKey()
+	}
+	if !pval.IsValid() {
+		switch fd.MapValue().Kind() {
+		case pref.MessageKind, pref.GroupKind:
+			// If value field is not set for message/group types, construct an
+			// empty one as default.
+			pval = mmap.NewValue()
+		default:
+			pval = fd.MapValue().Default()
+		}
+	}
+	mmap.Set(key, pval)
+	return nil
+}
+
+// unmarshalAny unmarshals an Any textproto. It can either be in expanded form
+// or non-expanded form.
+func (d decoder) unmarshalAny(m pref.Message, checkDelims bool) error {
+	var typeURL string
+	var bValue []byte
+
+	// hasFields tracks which valid fields have been seen in the loop below in
+	// order to flag an error if there are duplicates or conflicts. It may
+	// contain the strings "type_url", "value" and "expanded".  The literal
+	// "expanded" is used to indicate that the expanded form has been
+	// encountered already.
+	hasFields := map[string]bool{}
+
+	if checkDelims {
+		tok, err := d.Read()
+		if err != nil {
+			return err
+		}
+
+		if tok.Kind() != text.MessageOpen {
+			return d.unexpectedTokenError(tok)
+		}
+	}
+
+Loop:
+	for {
+		// Read field name. Can only have 3 possible field names, i.e. type_url,
+		// value and type URL name inside [].
+		tok, err := d.Read()
+		if err != nil {
+			return err
+		}
+		if typ := tok.Kind(); typ != text.Name {
+			if checkDelims {
+				if typ == text.MessageClose {
+					break Loop
+				}
+			} else if typ == text.EOF {
+				break Loop
+			}
+			return d.unexpectedTokenError(tok)
+		}
+
+		switch tok.NameKind() {
+		case text.IdentName:
+			// Both type_url and value fields require field separator :.
+			if !tok.HasSeparator() {
+				return d.syntaxError(tok.Pos(), "missing field separator :")
+			}
+
+			switch tok.IdentName() {
+			case "type_url":
+				if hasFields["type_url"] {
+					return d.newError(tok.Pos(), "duplicate Any type_url field")
+				}
+				if hasFields["expanded"] {
+					return d.newError(tok.Pos(), "conflict with [%s] field", typeURL)
+				}
+				tok, err := d.Read()
+				if err != nil {
+					return err
+				}
+				var ok bool
+				typeURL, ok = tok.String()
+				if !ok {
+					return d.newError(tok.Pos(), "invalid Any type_url: %v", tok.RawString())
+				}
+				hasFields["type_url"] = true
+
+			case "value":
+				if hasFields["value"] {
+					return d.newError(tok.Pos(), "duplicate Any value field")
+				}
+				if hasFields["expanded"] {
+					return d.newError(tok.Pos(), "conflict with [%s] field", typeURL)
+				}
+				tok, err := d.Read()
+				if err != nil {
+					return err
+				}
+				s, ok := tok.String()
+				if !ok {
+					return d.newError(tok.Pos(), "invalid Any value: %v", tok.RawString())
+				}
+				bValue = []byte(s)
+				hasFields["value"] = true
+
+			default:
+				if !d.opts.DiscardUnknown {
+					return d.newError(tok.Pos(), "invalid field name %q in google.protobuf.Any message", tok.RawString())
+				}
+			}
+
+		case text.TypeName:
+			if hasFields["expanded"] {
+				return d.newError(tok.Pos(), "cannot have more than one type")
+			}
+			if hasFields["type_url"] {
+				return d.newError(tok.Pos(), "conflict with type_url field")
+			}
+			typeURL = tok.TypeName()
+			var err error
+			bValue, err = d.unmarshalExpandedAny(typeURL, tok.Pos())
+			if err != nil {
+				return err
+			}
+			hasFields["expanded"] = true
+
+		default:
+			if !d.opts.DiscardUnknown {
+				return d.newError(tok.Pos(), "invalid field name %q in google.protobuf.Any message", tok.RawString())
+			}
+		}
+	}
+
+	fds := m.Descriptor().Fields()
+	if len(typeURL) > 0 {
+		m.Set(fds.ByNumber(fieldnum.Any_TypeUrl), pref.ValueOfString(typeURL))
+	}
+	if len(bValue) > 0 {
+		m.Set(fds.ByNumber(fieldnum.Any_Value), pref.ValueOfBytes(bValue))
+	}
+	return nil
+}
+
+func (d decoder) unmarshalExpandedAny(typeURL string, pos int) ([]byte, error) {
+	mt, err := d.opts.Resolver.FindMessageByURL(typeURL)
+	if err != nil {
+		return nil, d.newError(pos, "unable to resolve message [%v]: %v", typeURL, err)
+	}
+	// Create new message for the embedded message type and unmarshal the value
+	// field into it.
+	m := mt.New()
+	if err := d.unmarshalMessage(m, true); err != nil {
+		return nil, err
+	}
+	// Serialize the embedded message and return the resulting bytes.
+	b, err := proto.MarshalOptions{
+		AllowPartial:  true, // Never check required fields inside an Any.
+		Deterministic: true,
+	}.Marshal(m.Interface())
+	if err != nil {
+		return nil, d.newError(pos, "error in marshaling message into Any.value: %v", err)
+	}
+	return b, nil
+}
+
+// skipValue makes the decoder parse a field value in order to advance the read
+// to the next field. It relies on Read returning an error if the types are not
+// in valid sequence.
+func (d decoder) skipValue() error {
+	tok, err := d.Read()
+	if err != nil {
+		return err
+	}
+	// Only need to continue reading for messages and lists.
+	switch tok.Kind() {
+	case text.MessageOpen:
+		return d.skipMessageValue()
+
+	case text.ListOpen:
+		for {
+			tok, err := d.Read()
+			if err != nil {
+				return err
+			}
+			switch tok.Kind() {
+			case text.ListClose:
+				return nil
+			case text.MessageOpen:
+				return d.skipMessageValue()
+			default:
+				// Skip items. This will not validate whether skipped values are
+				// of the same type or not, same behavior as C++
+				// TextFormat::Parser::AllowUnknownField(true) version 3.8.0.
+				if err := d.skipValue(); err != nil {
+					return err
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// skipMessageValue makes the decoder parse and skip over all fields in a
+// message. It assumes that the previous read type is MessageOpen.
+func (d decoder) skipMessageValue() error {
+	for {
+		tok, err := d.Read()
+		if err != nil {
+			return err
+		}
+		switch tok.Kind() {
+		case text.MessageClose:
+			return nil
+		case text.Name:
+			if err := d.skipValue(); err != nil {
+				return err
+			}
+		}
+	}
+}
diff --git a/demo_test/vendor/google.golang.org/protobuf/encoding/prototext/doc.go b/demo_test/vendor/google.golang.org/protobuf/encoding/prototext/doc.go
new file mode 100644
index 0000000..162b4f9
--- /dev/null
+++ b/demo_test/vendor/google.golang.org/protobuf/encoding/prototext/doc.go
@@ -0,0 +1,7 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package prototext marshals and unmarshals protocol buffer messages as the
+// textproto format.
+package prototext
diff --git a/demo_test/vendor/google.golang.org/protobuf/encoding/prototext/encode.go b/demo_test/vendor/google.golang.org/protobuf/encoding/prototext/encode.go
new file mode 100644
index 0000000..83b65a6
--- /dev/null
+++ b/demo_test/vendor/google.golang.org/protobuf/encoding/prototext/encode.go
@@ -0,0 +1,410 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package prototext
+
+import (
+	"fmt"
+	"sort"
+	"strconv"
+	"unicode/utf8"
+
+	"google.golang.org/protobuf/encoding/protowire"
+	"google.golang.org/protobuf/internal/encoding/messageset"
+	"google.golang.org/protobuf/internal/encoding/text"
+	"google.golang.org/protobuf/internal/errors"
+	"google.golang.org/protobuf/internal/fieldnum"
+	"google.golang.org/protobuf/internal/flags"
+	"google.golang.org/protobuf/internal/mapsort"
+	"google.golang.org/protobuf/internal/pragma"
+	"google.golang.org/protobuf/proto"
+	pref "google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
+)
+
+const defaultIndent = "  "
+
+// Format formats the message as a multiline string.
+// This function is only intended for human consumption and ignores errors.
+// Do not depend on the output being stable. It may change over time across
+// different versions of the program.
+func Format(m proto.Message) string {
+	return MarshalOptions{Multiline: true}.Format(m)
+}
+
+// Marshal writes the given proto.Message in textproto format using default
+// options. Do not depend on the output being stable. It may change over time
+// across different versions of the program.
+func Marshal(m proto.Message) ([]byte, error) {
+	return MarshalOptions{}.Marshal(m)
+}
+
+// MarshalOptions is a configurable text format marshaler.
+type MarshalOptions struct {
+	pragma.NoUnkeyedLiterals
+
+	// Multiline specifies whether the marshaler should format the output in
+	// indented-form with every textual element on a new line.
+	// If Indent is an empty string, then an arbitrary indent is chosen.
+	Multiline bool
+
+	// Indent specifies the set of indentation characters to use in a multiline
+	// formatted output such that every entry is preceded by Indent and
+	// terminated by a newline. If non-empty, then Multiline is treated as true.
+	// Indent can only be composed of space or tab characters.
+	Indent string
+
+	// AllowPartial allows messages that have missing required fields to marshal
+	// without returning an error. If AllowPartial is false (the default),
+	// Marshal will return error if there are any missing required fields.
+	AllowPartial bool
+
+	// EmitUnknown specifies whether to emit unknown fields in the output.
+	// If specified, the unmarshaler may be unable to parse the output.
+	// The default is to exclude unknown fields.
+	EmitUnknown bool
+
+	// Resolver is used for looking up types when expanding google.protobuf.Any
+	// messages. If nil, this defaults to using protoregistry.GlobalTypes.
+	Resolver interface {
+		protoregistry.ExtensionTypeResolver
+		protoregistry.MessageTypeResolver
+	}
+}
+
+// Format formats the message as a string.
+// This method is only intended for human consumption and ignores errors.
+// Do not depend on the output being stable. It may change over time across
+// different versions of the program.
+func (o MarshalOptions) Format(m proto.Message) string {
+	if m == nil || !m.ProtoReflect().IsValid() {
+		return "<nil>" // invalid syntax, but okay since this is for debugging
+	}
+	o.AllowPartial = true
+	o.EmitUnknown = true
+	b, _ := o.Marshal(m)
+	return string(b)
+}
+
+// Marshal writes the given proto.Message in textproto format using options in
+// MarshalOptions object. Do not depend on the output being stable. It may
+// change over time across different versions of the program.
+func (o MarshalOptions) Marshal(m proto.Message) ([]byte, error) {
+	const outputASCII = false
+	var delims = [2]byte{'{', '}'}
+
+	if o.Multiline && o.Indent == "" {
+		o.Indent = defaultIndent
+	}
+	if o.Resolver == nil {
+		o.Resolver = protoregistry.GlobalTypes
+	}
+
+	internalEnc, err := text.NewEncoder(o.Indent, delims, outputASCII)
+	if err != nil {
+		return nil, err
+	}
+
+	enc := encoder{internalEnc, o}
+	err = enc.marshalMessage(m.ProtoReflect(), false)
+	if err != nil {
+		return nil, err
+	}
+	out := enc.Bytes()
+	if len(o.Indent) > 0 && len(out) > 0 {
+		out = append(out, '\n')
+	}
+	if o.AllowPartial {
+		return out, nil
+	}
+	return out, proto.CheckInitialized(m)
+}
+
+type encoder struct {
+	*text.Encoder
+	opts MarshalOptions
+}
+
+// marshalMessage marshals the given protoreflect.Message.
+func (e encoder) marshalMessage(m pref.Message, inclDelims bool) error {
+	messageDesc := m.Descriptor()
+	if !flags.ProtoLegacy && messageset.IsMessageSet(messageDesc) {
+		return errors.New("no support for proto1 MessageSets")
+	}
+
+	if inclDelims {
+		e.StartMessage()
+		defer e.EndMessage()
+	}
+
+	// Handle Any expansion.
+	if messageDesc.FullName() == "google.protobuf.Any" {
+		if e.marshalAny(m) {
+			return nil
+		}
+		// If unable to expand, continue on to marshal Any as a regular message.
+	}
+
+	// Marshal known fields.
+	fieldDescs := messageDesc.Fields()
+	size := fieldDescs.Len()
+	for i := 0; i < size; {
+		fd := fieldDescs.Get(i)
+		if od := fd.ContainingOneof(); od != nil {
+			fd = m.WhichOneof(od)
+			i += od.Fields().Len()
+		} else {
+			i++
+		}
+
+		if fd == nil || !m.Has(fd) {
+			continue
+		}
+
+		name := fd.Name()
+		// Use type name for group field name.
+		if fd.Kind() == pref.GroupKind {
+			name = fd.Message().Name()
+		}
+		val := m.Get(fd)
+		if err := e.marshalField(string(name), val, fd); err != nil {
+			return err
+		}
+	}
+
+	// Marshal extensions.
+	if err := e.marshalExtensions(m); err != nil {
+		return err
+	}
+
+	// Marshal unknown fields.
+	if e.opts.EmitUnknown {
+		e.marshalUnknown(m.GetUnknown())
+	}
+
+	return nil
+}
+
+// marshalField marshals the given field with protoreflect.Value.
+func (e encoder) marshalField(name string, val pref.Value, fd pref.FieldDescriptor) error {
+	switch {
+	case fd.IsList():
+		return e.marshalList(name, val.List(), fd)
+	case fd.IsMap():
+		return e.marshalMap(name, val.Map(), fd)
+	default:
+		e.WriteName(name)
+		return e.marshalSingular(val, fd)
+	}
+}
+
+// marshalSingular marshals the given non-repeated field value. This includes
+// all scalar types, enums, messages, and groups.
+func (e encoder) marshalSingular(val pref.Value, fd pref.FieldDescriptor) error {
+	kind := fd.Kind()
+	switch kind {
+	case pref.BoolKind:
+		e.WriteBool(val.Bool())
+
+	case pref.StringKind:
+		s := val.String()
+		if !utf8.ValidString(s) {
+			return errors.InvalidUTF8(string(fd.FullName()))
+		}
+		e.WriteString(s)
+
+	case pref.Int32Kind, pref.Int64Kind,
+		pref.Sint32Kind, pref.Sint64Kind,
+		pref.Sfixed32Kind, pref.Sfixed64Kind:
+		e.WriteInt(val.Int())
+
+	case pref.Uint32Kind, pref.Uint64Kind,
+		pref.Fixed32Kind, pref.Fixed64Kind:
+		e.WriteUint(val.Uint())
+
+	case pref.FloatKind:
+		// Encoder.WriteFloat handles the special numbers NaN and infinites.
+		e.WriteFloat(val.Float(), 32)
+
+	case pref.DoubleKind:
+		// Encoder.WriteFloat handles the special numbers NaN and infinites.
+		e.WriteFloat(val.Float(), 64)
+
+	case pref.BytesKind:
+		e.WriteString(string(val.Bytes()))
+
+	case pref.EnumKind:
+		num := val.Enum()
+		if desc := fd.Enum().Values().ByNumber(num); desc != nil {
+			e.WriteLiteral(string(desc.Name()))
+		} else {
+			// Use numeric value if there is no enum description.
+			e.WriteInt(int64(num))
+		}
+
+	case pref.MessageKind, pref.GroupKind:
+		return e.marshalMessage(val.Message(), true)
+
+	default:
+		panic(fmt.Sprintf("%v has unknown kind: %v", fd.FullName(), kind))
+	}
+	return nil
+}
+
+// marshalList marshals the given protoreflect.List as multiple name-value fields.
+func (e encoder) marshalList(name string, list pref.List, fd pref.FieldDescriptor) error {
+	size := list.Len()
+	for i := 0; i < size; i++ {
+		e.WriteName(name)
+		if err := e.marshalSingular(list.Get(i), fd); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// marshalMap marshals the given protoreflect.Map as multiple name-value fields.
+func (e encoder) marshalMap(name string, mmap pref.Map, fd pref.FieldDescriptor) error {
+	var err error
+	mapsort.Range(mmap, fd.MapKey().Kind(), func(key pref.MapKey, val pref.Value) bool {
+		e.WriteName(name)
+		e.StartMessage()
+		defer e.EndMessage()
+
+		e.WriteName("key")
+		err = e.marshalSingular(key.Value(), fd.MapKey())
+		if err != nil {
+			return false
+		}
+
+		e.WriteName("value")
+		err = e.marshalSingular(val, fd.MapValue())
+		if err != nil {
+			return false
+		}
+		return true
+	})
+	return err
+}
+
+// marshalExtensions marshals extension fields.
+func (e encoder) marshalExtensions(m pref.Message) error {
+	type entry struct {
+		key   string
+		value pref.Value
+		desc  pref.FieldDescriptor
+	}
+
+	// Get a sorted list based on field key first.
+	var entries []entry
+	m.Range(func(fd pref.FieldDescriptor, v pref.Value) bool {
+		if !fd.IsExtension() {
+			return true
+		}
+		// For MessageSet extensions, the name used is the parent message.
+		name := fd.FullName()
+		if messageset.IsMessageSetExtension(fd) {
+			name = name.Parent()
+		}
+		entries = append(entries, entry{
+			key:   string(name),
+			value: v,
+			desc:  fd,
+		})
+		return true
+	})
+	// Sort extensions lexicographically.
+	sort.Slice(entries, func(i, j int) bool {
+		return entries[i].key < entries[j].key
+	})
+
+	// Write out sorted list.
+	for _, entry := range entries {
+		// Extension field name is the proto field name enclosed in [].
+		name := "[" + entry.key + "]"
+		if err := e.marshalField(name, entry.value, entry.desc); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// marshalUnknown parses the given []byte and marshals fields out.
+// This function assumes proper encoding in the given []byte.
+func (e encoder) marshalUnknown(b []byte) {
+	const dec = 10
+	const hex = 16
+	for len(b) > 0 {
+		num, wtype, n := protowire.ConsumeTag(b)
+		b = b[n:]
+		e.WriteName(strconv.FormatInt(int64(num), dec))
+
+		switch wtype {
+		case protowire.VarintType:
+			var v uint64
+			v, n = protowire.ConsumeVarint(b)
+			e.WriteUint(v)
+		case protowire.Fixed32Type:
+			var v uint32
+			v, n = protowire.ConsumeFixed32(b)
+			e.WriteLiteral("0x" + strconv.FormatUint(uint64(v), hex))
+		case protowire.Fixed64Type:
+			var v uint64
+			v, n = protowire.ConsumeFixed64(b)
+			e.WriteLiteral("0x" + strconv.FormatUint(v, hex))
+		case protowire.BytesType:
+			var v []byte
+			v, n = protowire.ConsumeBytes(b)
+			e.WriteString(string(v))
+		case protowire.StartGroupType:
+			e.StartMessage()
+			var v []byte
+			v, n = protowire.ConsumeGroup(num, b)
+			e.marshalUnknown(v)
+			e.EndMessage()
+		default:
+			panic(fmt.Sprintf("prototext: error parsing unknown field wire type: %v", wtype))
+		}
+
+		b = b[n:]
+	}
+}
+
+// marshalAny marshals the given google.protobuf.Any message in expanded form.
+// It returns true if it was able to marshal, else false.
+func (e encoder) marshalAny(any pref.Message) bool {
+	// Construct the embedded message.
+	fds := any.Descriptor().Fields()
+	fdType := fds.ByNumber(fieldnum.Any_TypeUrl)
+	typeURL := any.Get(fdType).String()
+	mt, err := e.opts.Resolver.FindMessageByURL(typeURL)
+	if err != nil {
+		return false
+	}
+	m := mt.New().Interface()
+
+	// Unmarshal bytes into embedded message.
+	fdValue := fds.ByNumber(fieldnum.Any_Value)
+	value := any.Get(fdValue)
+	err = proto.UnmarshalOptions{
+		AllowPartial: true,
+		Resolver:     e.opts.Resolver,
+	}.Unmarshal(value.Bytes(), m)
+	if err != nil {
+		return false
+	}
+
+	// Get current encoder position. If marshaling fails, reset encoder output
+	// back to this position.
+	pos := e.Snapshot()
+
+	// Field name is the proto field name enclosed in [].
+	e.WriteName("[" + typeURL + "]")
+	err = e.marshalMessage(m.ProtoReflect(), true)
+	if err != nil {
+		e.Reset(pos)
+		return false
+	}
+	return true
+}
diff --git a/demo_test/vendor/google.golang.org/protobuf/encoding/protowire/wire.go b/demo_test/vendor/google.golang.org/protobuf/encoding/protowire/wire.go
new file mode 100644
index 0000000..a427f8b
--- /dev/null
+++ b/demo_test/vendor/google.golang.org/protobuf/encoding/protowire/wire.go
@@ -0,0 +1,538 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package protowire parses and formats the raw wire encoding.
+// See https://developers.google.com/protocol-buffers/docs/encoding.
+//
+// For marshaling and unmarshaling entire protobuf messages,
+// use the "google.golang.org/protobuf/proto" package instead.
+package protowire
+
+import (
+	"io"
+	"math"
+	"math/bits"
+
+	"google.golang.org/protobuf/internal/errors"
+)
+
+// Number represents the field number.
+type Number int32
+
+const (
+	MinValidNumber      Number = 1
+	FirstReservedNumber Number = 19000
+	LastReservedNumber  Number = 19999
+	MaxValidNumber      Number = 1<<29 - 1
+)
+
+// IsValid reports whether the field number is semantically valid.
+//
+// Note that while numbers within the reserved range are semantically invalid,
+// they are syntactically valid in the wire format.
+// Implementations may treat records with reserved field numbers as unknown.
+func (n Number) IsValid() bool {
+	return MinValidNumber <= n && n < FirstReservedNumber || LastReservedNumber < n && n <= MaxValidNumber
+}
+
+// Type represents the wire type.
+type Type int8
+
+const (
+	VarintType     Type = 0
+	Fixed32Type    Type = 5
+	Fixed64Type    Type = 1
+	BytesType      Type = 2
+	StartGroupType Type = 3
+	EndGroupType   Type = 4
+)
+
+const (
+	_ = -iota
+	errCodeTruncated
+	errCodeFieldNumber
+	errCodeOverflow
+	errCodeReserved
+	errCodeEndGroup
+)
+
+var (
+	errFieldNumber = errors.New("invalid field number")
+	errOverflow    = errors.New("variable length integer overflow")
+	errReserved    = errors.New("cannot parse reserved wire type")
+	errEndGroup    = errors.New("mismatching end group marker")
+	errParse       = errors.New("parse error")
+)
+
+// ParseError converts an error code into an error value.
+// This returns nil if n is a non-negative number.
+func ParseError(n int) error {
+	if n >= 0 {
+		return nil
+	}
+	switch n {
+	case errCodeTruncated:
+		return io.ErrUnexpectedEOF
+	case errCodeFieldNumber:
+		return errFieldNumber
+	case errCodeOverflow:
+		return errOverflow
+	case errCodeReserved:
+		return errReserved
+	case errCodeEndGroup:
+		return errEndGroup
+	default:
+		return errParse
+	}
+}
+
+// ConsumeField parses an entire field record (both tag and value) and returns
+// the field number, the wire type, and the total length.
+// This returns a negative length upon an error (see ParseError).
+//
+// The total length includes the tag header and the end group marker (if the
+// field is a group).
+func ConsumeField(b []byte) (Number, Type, int) {
+	num, typ, n := ConsumeTag(b)
+	if n < 0 {
+		return 0, 0, n // forward error code
+	}
+	m := ConsumeFieldValue(num, typ, b[n:])
+	if m < 0 {
+		return 0, 0, m // forward error code
+	}
+	return num, typ, n + m
+}
+
+// ConsumeFieldValue parses a field value and returns its length.
+// This assumes that the field Number and wire Type have already been parsed.
+// This returns a negative length upon an error (see ParseError).
+//
+// When parsing a group, the length includes the end group marker and
+// the end group is verified to match the starting field number.
+func ConsumeFieldValue(num Number, typ Type, b []byte) (n int) {
+	switch typ {
+	case VarintType:
+		_, n = ConsumeVarint(b)
+		return n
+	case Fixed32Type:
+		_, n = ConsumeFixed32(b)
+		return n
+	case Fixed64Type:
+		_, n = ConsumeFixed64(b)
+		return n
+	case BytesType:
+		_, n = ConsumeBytes(b)
+		return n
+	case StartGroupType:
+		n0 := len(b)
+		for {
+			num2, typ2, n := ConsumeTag(b)
+			if n < 0 {
+				return n // forward error code
+			}
+			b = b[n:]
+			if typ2 == EndGroupType {
+				if num != num2 {
+					return errCodeEndGroup
+				}
+				return n0 - len(b)
+			}
+
+			n = ConsumeFieldValue(num2, typ2, b)
+			if n < 0 {
+				return n // forward error code
+			}
+			b = b[n:]
+		}
+	case EndGroupType:
+		return errCodeEndGroup
+	default:
+		return errCodeReserved
+	}
+}
+
+// AppendTag encodes num and typ as a varint-encoded tag and appends it to b.
+func AppendTag(b []byte, num Number, typ Type) []byte {
+	return AppendVarint(b, EncodeTag(num, typ))
+}
+
+// ConsumeTag parses b as a varint-encoded tag, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeTag(b []byte) (Number, Type, int) {
+	v, n := ConsumeVarint(b)
+	if n < 0 {
+		return 0, 0, n // forward error code
+	}
+	num, typ := DecodeTag(v)
+	if num < MinValidNumber {
+		return 0, 0, errCodeFieldNumber
+	}
+	return num, typ, n
+}
+
+func SizeTag(num Number) int {
+	return SizeVarint(EncodeTag(num, 0)) // wire type has no effect on size
+}
+
+// AppendVarint appends v to b as a varint-encoded uint64.
+func AppendVarint(b []byte, v uint64) []byte {
+	switch {
+	case v < 1<<7:
+		b = append(b, byte(v))
+	case v < 1<<14:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte(v>>7))
+	case v < 1<<21:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte(v>>14))
+	case v < 1<<28:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte(v>>21))
+	case v < 1<<35:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte(v>>28))
+	case v < 1<<42:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte(v>>35))
+	case v < 1<<49:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte((v>>35)&0x7f|0x80),
+			byte(v>>42))
+	case v < 1<<56:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte((v>>35)&0x7f|0x80),
+			byte((v>>42)&0x7f|0x80),
+			byte(v>>49))
+	case v < 1<<63:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte((v>>35)&0x7f|0x80),
+			byte((v>>42)&0x7f|0x80),
+			byte((v>>49)&0x7f|0x80),
+			byte(v>>56))
+	default:
+		b = append(b,
+			byte((v>>0)&0x7f|0x80),
+			byte((v>>7)&0x7f|0x80),
+			byte((v>>14)&0x7f|0x80),
+			byte((v>>21)&0x7f|0x80),
+			byte((v>>28)&0x7f|0x80),
+			byte((v>>35)&0x7f|0x80),
+			byte((v>>42)&0x7f|0x80),
+			byte((v>>49)&0x7f|0x80),
+			byte((v>>56)&0x7f|0x80),
+			1)
+	}
+	return b
+}
+
+// ConsumeVarint parses b as a varint-encoded uint64, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeVarint(b []byte) (v uint64, n int) {
+	var y uint64
+	if len(b) <= 0 {
+		return 0, errCodeTruncated
+	}
+	v = uint64(b[0])
+	if v < 0x80 {
+		return v, 1
+	}
+	v -= 0x80
+
+	if len(b) <= 1 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[1])
+	v += y << 7
+	if y < 0x80 {
+		return v, 2
+	}
+	v -= 0x80 << 7
+
+	if len(b) <= 2 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[2])
+	v += y << 14
+	if y < 0x80 {
+		return v, 3
+	}
+	v -= 0x80 << 14
+
+	if len(b) <= 3 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[3])
+	v += y << 21
+	if y < 0x80 {
+		return v, 4
+	}
+	v -= 0x80 << 21
+
+	if len(b) <= 4 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[4])
+	v += y << 28
+	if y < 0x80 {
+		return v, 5
+	}
+	v -= 0x80 << 28
+
+	if len(b) <= 5 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[5])
+	v += y << 35
+	if y < 0x80 {
+		return v, 6
+	}
+	v -= 0x80 << 35
+
+	if len(b) <= 6 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[6])
+	v += y << 42
+	if y < 0x80 {
+		return v, 7
+	}
+	v -= 0x80 << 42
+
+	if len(b) <= 7 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[7])
+	v += y << 49
+	if y < 0x80 {
+		return v, 8
+	}
+	v -= 0x80 << 49
+
+	if len(b) <= 8 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[8])
+	v += y << 56
+	if y < 0x80 {
+		return v, 9
+	}
+	v -= 0x80 << 56
+
+	if len(b) <= 9 {
+		return 0, errCodeTruncated
+	}
+	y = uint64(b[9])
+	v += y << 63
+	if y < 2 {
+		return v, 10
+	}
+	return 0, errCodeOverflow
+}
+
+// SizeVarint returns the encoded size of a varint.
+// The size is guaranteed to be within 1 and 10, inclusive.
+func SizeVarint(v uint64) int {
+	// This computes 1 + (bits.Len64(v)-1)/7.
+	// 9/64 is a good enough approximation of 1/7
+	return int(9*uint32(bits.Len64(v))+64) / 64
+}
+
+// AppendFixed32 appends v to b as a little-endian uint32.
+func AppendFixed32(b []byte, v uint32) []byte {
+	return append(b,
+		byte(v>>0),
+		byte(v>>8),
+		byte(v>>16),
+		byte(v>>24))
+}
+
+// ConsumeFixed32 parses b as a little-endian uint32, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeFixed32(b []byte) (v uint32, n int) {
+	if len(b) < 4 {
+		return 0, errCodeTruncated
+	}
+	v = uint32(b[0])<<0 | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+	return v, 4
+}
+
+// SizeFixed32 returns the encoded size of a fixed32; which is always 4.
+func SizeFixed32() int {
+	return 4
+}
+
+// AppendFixed64 appends v to b as a little-endian uint64.
+func AppendFixed64(b []byte, v uint64) []byte {
+	return append(b,
+		byte(v>>0),
+		byte(v>>8),
+		byte(v>>16),
+		byte(v>>24),
+		byte(v>>32),
+		byte(v>>40),
+		byte(v>>48),
+		byte(v>>56))
+}
+
+// ConsumeFixed64 parses b as a little-endian uint64, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeFixed64(b []byte) (v uint64, n int) {
+	if len(b) < 8 {
+		return 0, errCodeTruncated
+	}
+	v = uint64(b[0])<<0 | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+	return v, 8
+}
+
+// SizeFixed64 returns the encoded size of a fixed64; which is always 8.
+func SizeFixed64() int {
+	return 8
+}
+
+// AppendBytes appends v to b as a length-prefixed bytes value.
+func AppendBytes(b []byte, v []byte) []byte {
+	return append(AppendVarint(b, uint64(len(v))), v...)
+}
+
+// ConsumeBytes parses b as a length-prefixed bytes value, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeBytes(b []byte) (v []byte, n int) {
+	m, n := ConsumeVarint(b)
+	if n < 0 {
+		return nil, n // forward error code
+	}
+	if m > uint64(len(b[n:])) {
+		return nil, errCodeTruncated
+	}
+	return b[n:][:m], n + int(m)
+}
+
+// SizeBytes returns the encoded size of a length-prefixed bytes value,
+// given only the length.
+func SizeBytes(n int) int {
+	return SizeVarint(uint64(n)) + n
+}
+
+// AppendString appends v to b as a length-prefixed bytes value.
+func AppendString(b []byte, v string) []byte {
+	return append(AppendVarint(b, uint64(len(v))), v...)
+}
+
+// ConsumeString parses b as a length-prefixed bytes value, reporting its length.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeString(b []byte) (v string, n int) {
+	bb, n := ConsumeBytes(b)
+	return string(bb), n
+}
+
+// AppendGroup appends v to b as group value, with a trailing end group marker.
+// The value v must not contain the end marker.
+func AppendGroup(b []byte, num Number, v []byte) []byte {
+	return AppendVarint(append(b, v...), EncodeTag(num, EndGroupType))
+}
+
+// ConsumeGroup parses b as a group value until the trailing end group marker,
+// and verifies that the end marker matches the provided num. The value v
+// does not contain the end marker, while the length does contain the end marker.
+// This returns a negative length upon an error (see ParseError).
+func ConsumeGroup(num Number, b []byte) (v []byte, n int) {
+	n = ConsumeFieldValue(num, StartGroupType, b)
+	if n < 0 {
+		return nil, n // forward error code
+	}
+	b = b[:n]
+
+	// Truncate off end group marker, but need to handle denormalized varints.
+	// Assuming end marker is never 0 (which is always the case since
+	// EndGroupType is non-zero), we can truncate all trailing bytes where the
+	// lower 7 bits are all zero (implying that the varint is denormalized).
+	for len(b) > 0 && b[len(b)-1]&0x7f == 0 {
+		b = b[:len(b)-1]
+	}
+	b = b[:len(b)-SizeTag(num)]
+	return b, n
+}
+
+// SizeGroup returns the encoded size of a group, given only the length.
+func SizeGroup(num Number, n int) int {
+	return n + SizeTag(num)
+}
+
+// DecodeTag decodes the field Number and wire Type from its unified form.
+// The Number is -1 if the decoded field number overflows int32.
+// Other than overflow, this does not check for field number validity.
+func DecodeTag(x uint64) (Number, Type) {
+	// NOTE: MessageSet allows for larger field numbers than normal.
+	if x>>3 > uint64(math.MaxInt32) {
+		return -1, 0
+	}
+	return Number(x >> 3), Type(x & 7)
+}
+
+// EncodeTag encodes the field Number and wire Type into its unified form.
+func EncodeTag(num Number, typ Type) uint64 {
+	return uint64(num)<<3 | uint64(typ&7)
+}
+
+// DecodeZigZag decodes a zig-zag-encoded uint64 as an int64.
+//	Input:  {…,  5,  3,  1,  0,  2,  4,  6, …}
+//	Output: {…, -3, -2, -1,  0, +1, +2, +3, …}
+func DecodeZigZag(x uint64) int64 {
+	return int64(x>>1) ^ int64(x)<<63>>63
+}
+
+// EncodeZigZag encodes an int64 as a zig-zag-encoded uint64.
+//	Input:  {…, -3, -2, -1,  0, +1, +2, +3, …}
+//	Output: {…,  5,  3,  1,  0,  2,  4,  6, …}
+func EncodeZigZag(x int64) uint64 {
+	return uint64(x<<1) ^ uint64(x>>63)
+}
+
+// DecodeBool decodes a uint64 as a bool.
+//	Input:  {    0,    1,    2, …}
+//	Output: {false, true, true, …}
+func DecodeBool(x uint64) bool {
+	return x != 0
+}
+
+// EncodeBool encodes a bool as a uint64.
+//	Input:  {false, true}
+//	Output: {    0,    1}
+func EncodeBool(x bool) uint64 {
+	if x {
+		return 1
+	}
+	return 0
+}