diff --git a/vendor/github.com/hashicorp/go-immutable-radix/iter.go b/vendor/github.com/hashicorp/go-immutable-radix/iter.go
new file mode 100644
index 0000000..1ecaf83
--- /dev/null
+++ b/vendor/github.com/hashicorp/go-immutable-radix/iter.go
@@ -0,0 +1,188 @@
+package iradix
+
+import (
+	"bytes"
+)
+
+// Iterator is used to iterate over a set of nodes
+// in pre-order
+type Iterator struct {
+	node  *Node
+	stack []edges
+}
+
+// SeekPrefixWatch is used to seek the iterator to a given prefix
+// and returns the watch channel of the finest granularity
+func (i *Iterator) SeekPrefixWatch(prefix []byte) (watch <-chan struct{}) {
+	// Wipe the stack
+	i.stack = nil
+	n := i.node
+	watch = n.mutateCh
+	search := prefix
+	for {
+		// Check for key exhaution
+		if len(search) == 0 {
+			i.node = n
+			return
+		}
+
+		// Look for an edge
+		_, n = n.getEdge(search[0])
+		if n == nil {
+			i.node = nil
+			return
+		}
+
+		// Update to the finest granularity as the search makes progress
+		watch = n.mutateCh
+
+		// Consume the search prefix
+		if bytes.HasPrefix(search, n.prefix) {
+			search = search[len(n.prefix):]
+
+		} else if bytes.HasPrefix(n.prefix, search) {
+			i.node = n
+			return
+		} else {
+			i.node = nil
+			return
+		}
+	}
+}
+
+// SeekPrefix is used to seek the iterator to a given prefix
+func (i *Iterator) SeekPrefix(prefix []byte) {
+	i.SeekPrefixWatch(prefix)
+}
+
+func (i *Iterator) recurseMin(n *Node) *Node {
+	// Traverse to the minimum child
+	if n.leaf != nil {
+		return n
+	}
+	if len(n.edges) > 0 {
+		// Add all the other edges to the stack (the min node will be added as
+		// we recurse)
+		i.stack = append(i.stack, n.edges[1:])
+		return i.recurseMin(n.edges[0].node)
+	}
+	// Shouldn't be possible
+	return nil
+}
+
+// SeekLowerBound is used to seek the iterator to the smallest key that is
+// greater or equal to the given key. There is no watch variant as it's hard to
+// predict based on the radix structure which node(s) changes might affect the
+// result.
+func (i *Iterator) SeekLowerBound(key []byte) {
+	// Wipe the stack. Unlike Prefix iteration, we need to build the stack as we
+	// go because we need only a subset of edges of many nodes in the path to the
+	// leaf with the lower bound.
+	i.stack = []edges{}
+	n := i.node
+	search := key
+
+	found := func(n *Node) {
+		i.node = n
+		i.stack = append(i.stack, edges{edge{node: n}})
+	}
+
+	for {
+		// Compare current prefix with the search key's same-length prefix.
+		var prefixCmp int
+		if len(n.prefix) < len(search) {
+			prefixCmp = bytes.Compare(n.prefix, search[0:len(n.prefix)])
+		} else {
+			prefixCmp = bytes.Compare(n.prefix, search)
+		}
+
+		if prefixCmp > 0 {
+			// Prefix is larger, that means the lower bound is greater than the search
+			// and from now on we need to follow the minimum path to the smallest
+			// leaf under this subtree.
+			n = i.recurseMin(n)
+			if n != nil {
+				found(n)
+			}
+			return
+		}
+
+		if prefixCmp < 0 {
+			// Prefix is smaller than search prefix, that means there is no lower
+			// bound
+			i.node = nil
+			return
+		}
+
+		// Prefix is equal, we are still heading for an exact match. If this is a
+		// leaf we're done.
+		if n.leaf != nil {
+			if bytes.Compare(n.leaf.key, key) < 0 {
+				i.node = nil
+				return
+			}
+			found(n)
+			return
+		}
+
+		// Consume the search prefix
+		if len(n.prefix) > len(search) {
+			search = []byte{}
+		} else {
+			search = search[len(n.prefix):]
+		}
+
+		// Otherwise, take the lower bound next edge.
+		idx, lbNode := n.getLowerBoundEdge(search[0])
+		if lbNode == nil {
+			i.node = nil
+			return
+		}
+
+		// Create stack edges for the all strictly higher edges in this node.
+		if idx+1 < len(n.edges) {
+			i.stack = append(i.stack, n.edges[idx+1:])
+		}
+
+		i.node = lbNode
+		// Recurse
+		n = lbNode
+	}
+}
+
+// Next returns the next node in order
+func (i *Iterator) Next() ([]byte, interface{}, bool) {
+	// Initialize our stack if needed
+	if i.stack == nil && i.node != nil {
+		i.stack = []edges{
+			edges{
+				edge{node: i.node},
+			},
+		}
+	}
+
+	for len(i.stack) > 0 {
+		// Inspect the last element of the stack
+		n := len(i.stack)
+		last := i.stack[n-1]
+		elem := last[0].node
+
+		// Update the stack
+		if len(last) > 1 {
+			i.stack[n-1] = last[1:]
+		} else {
+			i.stack = i.stack[:n-1]
+		}
+
+		// Push the edges onto the frontier
+		if len(elem.edges) > 0 {
+			i.stack = append(i.stack, elem.edges)
+		}
+
+		// Return the leaf values if any
+		if elem.leaf != nil {
+			return elem.leaf.key, elem.leaf.val, true
+		}
+	}
+	return nil, nil, false
+}