diff --git a/plyproto/model.py b/plyproto/model.py
index 5369fde..802cf47 100644
--- a/plyproto/model.py
+++ b/plyproto/model.py
@@ -45,9 +45,22 @@
     def v(self, obj, visitor):
         if obj == None:
             return
-        if not hasattr(obj, "accept"):
-            return
-        obj.accept(visitor)
+        elif hasattr(obj, "accept"):
+            obj.accept(visitor)
+        elif isinstance(obj, list):
+            for s in obj:
+                self.v(s, visitor)
+            pass
+        pass
+
+    @staticmethod
+    def p(obj, parent):
+        if isinstance(obj, list):
+            for s in obj:
+                Base.p(s, parent)
+
+        if hasattr(obj, "parent"):
+            obj.parent = parent
 
 # Lexical unit - contains lexspan and linespan for later analysis.
 class LU(Base):
@@ -132,7 +145,7 @@
         super(PackageStatement, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
 
     def accept(self, visitor):
         visitor.visit_PackageStatement(self)
@@ -142,7 +155,7 @@
         super(ImportStatement, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
 
     def accept(self, visitor):
         visitor.visit_ImportStatement(self)
@@ -152,9 +165,9 @@
         super(OptionStatement, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name', 'value']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
         self.value = value
-        self.value.parent = self
+        Base.p(self.value, self)
 
     def accept(self, visitor):
         visitor.visit_OptionStatement(self)
@@ -164,9 +177,9 @@
         super(FieldDirective, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name', 'value']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
         self.value = value
-        self.value.parent = self
+        Base.p(self.value, self)
 
     def accept(self, visitor):
         if visitor.visit_FieldDirective(self):
@@ -178,7 +191,7 @@
         super(FieldType, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
 
     def accept(self, visitor):
         if visitor.visit_FieldType(self):
@@ -189,16 +202,15 @@
         super(FieldDefinition, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['field_modifier', 'ftype', 'name', 'fieldId', 'fieldDirective']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
         self.field_modifier = field_modifier
-        self.field_modifier.parent = self
+        Base.p(self.field_modifier, self)
         self.ftype = ftype
-        self.ftype.parent = self
+        Base.p(self.ftype, self)
         self.fieldId = fieldId
-        self.fieldId.parent = self
+        Base.p(self.fieldId, self)
         self.fieldDirective = fieldDirective
-        for s in self.fieldDirective:
-            s.parent = self
+        Base.p(self.fieldDirective, self)
 
     def accept(self, visitor):
         if visitor.visit_FieldDefinition(self):
@@ -206,17 +218,16 @@
             self.v(self.field_modifier, visitor)
             self.v(self.ftype, visitor)
             self.v(self.fieldId, visitor)
-            for s in self.fieldDirective:
-                self.v(s, visitor)
+            self.v(self.fieldDirective, visitor)
 
 class EnumFieldDefinition(SourceElement):
     def __init__(self, name, fieldId, linespan=None, lexspan=None, p=None):
         super(EnumFieldDefinition, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name', 'fieldId']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
         self.fieldId = fieldId
-        self.fieldId.parent = self
+        Base.p(self.fieldId, self)
 
     def accept(self, visitor):
         if visitor.visit_EnumFieldDefinition(self):
@@ -228,59 +239,53 @@
         super(EnumDefinition, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name', 'body']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
         self.body = body
-        for s in self.body:
-            s.parent = self
+        Base.p(self.body, self)
 
     def accept(self, visitor):
         if visitor.visit_EnumDefinition(self):
             self.v(self.name, visitor)
-            for s in self.body:
-                s.accept(visitor)
+            self.v(self.body, visitor)
 
 class MessageDefinition(SourceElement):
     def __init__(self, name, body, linespan=None, lexspan=None, p=None):
         super(MessageDefinition, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name', 'body']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
         self.body = body
-        for s in self.body:
-            s.parent = self
+        Base.p(self.body, self)
 
     def accept(self, visitor):
         if visitor.visit_MessageDefinition(self):
             self.v(self.name, visitor)
-            for s in self.body:
-                s.accept(visitor)
+            self.v(self.body, visitor)
 
 class MessageExtension(SourceElement):
     def __init__(self, name, body, linespan=None, lexspan=None, p=None):
         super(MessageExtension, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name', 'body']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
         self.body = body
-        for s in self.body:
-            s.parent = self
+        Base.p(self.body, self)
 
     def accept(self, visitor):
         if visitor.visit_MessageExtension(self):
             self.v(self.name, visitor)
-            for s in self.body:
-                s.accept(visitor)
+            self.v(self.body, visitor)
 
 class MethodDefinition(SourceElement):
     def __init__(self, name, name2, name3, linespan=None, lexspan=None, p=None):
         super(MethodDefinition, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name', 'name2', 'name3']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
         self.name2 = name2
-        self.name.parent = self
+        Base.p(self.name, self)
         self.name3 = name3
-        self.name.parent = self
+        Base.p(self.name, self)
 
     def accept(self, visitor):
         if visitor.visit_MethodDefinition(self):
@@ -293,14 +298,14 @@
         super(ServiceDefinition, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['name', 'body']
         self.name = name
-        self.name.parent = self
+        Base.p(self.name, self)
         self.body = body
+        Base.p(self.body, self)
 
     def accept(self, visitor):
         if visitor.visit_ServiceDefinition(self):
             self.v(self.name, visitor)
-            for s in self.body:
-                s.accept(visitor)
+            self.v(self.body, visitor)
 
 class ExtensionsMax(SourceElement):
     pass
@@ -310,9 +315,9 @@
         super(ExtensionsDirective, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['fromVal', 'toVal']
         self.fromVal = fromVal
-        self.fromVal.parent = self
+        Base.p(self.fromVal, self)
         self.toVal = toVal
-        self.toVal.parent = self
+        Base.p(self.toVal, self)
 
     def accept(self, visitor):
         if visitor.visit_ExtensionsDirective(self):
@@ -380,13 +385,11 @@
         super(ProtoFile, self).__init__(linespan=linespan, lexspan=lexspan, p=p)
         self._fields += ['pkg', 'body']
         self.pkg = pkg
-        self.pkg.parent = self
+        Base.p(self.pkg, self)
         self.body = body
-        for s in self.body:
-            s.parent = self
+        Base.p(self.body, self)
 
     def accept(self, visitor):
         if visitor.visit_Proto(self):
             self.v(self.pkg, visitor)
-            for s in self.body:
-                s.accept(visitor)
+            self.v(self.body, visitor)