diff --git a/python/flatbuffers/builder.py b/python/flatbuffers/builder.py
new file mode 100644
index 0000000..d04ee85
--- /dev/null
+++ b/python/flatbuffers/builder.py
@@ -0,0 +1,755 @@
+# Copyright 2014 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from . import number_types as N
+from .number_types import (UOffsetTFlags, SOffsetTFlags, VOffsetTFlags)
+
+from . import encode
+from . import packer
+
+from . import compat
+from .compat import range_func
+from .compat import memoryview_type
+from .compat import import_numpy, NumpyRequiredForThisFeature
+
+np = import_numpy()
+## @file
+## @addtogroup flatbuffers_python_api
+## @{
+
+## @cond FLATBUFFERS_INTERNAL
+class OffsetArithmeticError(RuntimeError):
+    """
+    Error caused by an Offset arithmetic error. Probably caused by bad
+    writing of fields. This is considered an unreachable situation in
+    normal circumstances.
+    """
+    pass
+
+
+class IsNotNestedError(RuntimeError):
+    """
+    Error caused by using a Builder to write Object data when not inside
+    an Object.
+    """
+    pass
+
+
+class IsNestedError(RuntimeError):
+    """
+    Error caused by using a Builder to begin an Object when an Object is
+    already being built.
+    """
+    pass
+
+
+class StructIsNotInlineError(RuntimeError):
+    """
+    Error caused by using a Builder to write a Struct at a location that
+    is not the current Offset.
+    """
+    pass
+
+
+class BuilderSizeError(RuntimeError):
+    """
+    Error caused by causing a Builder to exceed the hardcoded limit of 2
+    gigabytes.
+    """
+    pass
+
+class BuilderNotFinishedError(RuntimeError):
+    """
+    Error caused by not calling `Finish` before calling `Output`.
+    """
+    pass
+
+
+# VtableMetadataFields is the count of metadata fields in each vtable.
+VtableMetadataFields = 2
+## @endcond
+
+class Builder(object):
+    """ A Builder is used to construct one or more FlatBuffers.
+
+    Typically, Builder objects will be used from code generated by the `flatc`
+    compiler.
+
+    A Builder constructs byte buffers in a last-first manner for simplicity and
+    performance during reading.
+
+    Internally, a Builder is a state machine for creating FlatBuffer objects.
+
+    It holds the following internal state:
+        - Bytes: an array of bytes.
+        - current_vtable: a list of integers.
+        - vtables: a hash of vtable entries.
+
+    Attributes:
+      Bytes: The internal `bytearray` for the Builder.
+      finished: A boolean determining if the Builder has been finalized.
+    """
+
+    ## @cond FLATBUFFERS_INTENRAL
+    __slots__ = ("Bytes", "current_vtable", "head", "minalign", "objectEnd",
+                 "vtables", "nested", "finished")
+
+    """Maximum buffer size constant, in bytes.
+
+    Builder will never allow it's buffer grow over this size.
+    Currently equals 2Gb.
+    """
+    MAX_BUFFER_SIZE = 2**31
+    ## @endcond
+
+    def __init__(self, initialSize):
+        """Initializes a Builder of size `initial_size`.
+
+        The internal buffer is grown as needed.
+        """
+
+        if not (0 <= initialSize <= Builder.MAX_BUFFER_SIZE):
+            msg = "flatbuffers: Cannot create Builder larger than 2 gigabytes."
+            raise BuilderSizeError(msg)
+
+        self.Bytes = bytearray(initialSize)
+        ## @cond FLATBUFFERS_INTERNAL
+        self.current_vtable = None
+        self.head = UOffsetTFlags.py_type(initialSize)
+        self.minalign = 1
+        self.objectEnd = None
+        self.vtables = {}
+        self.nested = False
+        ## @endcond
+        self.finished = False
+
+
+    def Output(self):
+        """Return the portion of the buffer that has been used for writing data.
+
+        This is the typical way to access the FlatBuffer data inside the
+        builder. If you try to access `Builder.Bytes` directly, you would need
+        to manually index it with `Head()`, since the buffer is constructed
+        backwards.
+
+        It raises BuilderNotFinishedError if the buffer has not been finished
+        with `Finish`.
+        """
+
+        if not self.finished:
+            raise BuilderNotFinishedError()
+
+        return self.Bytes[self.Head():]
+
+    ## @cond FLATBUFFERS_INTERNAL
+    def StartObject(self, numfields):
+        """StartObject initializes bookkeeping for writing a new object."""
+
+        self.assertNotNested()
+
+        # use 32-bit offsets so that arithmetic doesn't overflow.
+        self.current_vtable = [0 for _ in range_func(numfields)]
+        self.objectEnd = self.Offset()
+        self.nested = True
+
+    def WriteVtable(self):
+        """
+        WriteVtable serializes the vtable for the current object, if needed.
+
+        Before writing out the vtable, this checks pre-existing vtables for
+        equality to this one. If an equal vtable is found, point the object to
+        the existing vtable and return.
+
+        Because vtable values are sensitive to alignment of object data, not
+        all logically-equal vtables will be deduplicated.
+
+        A vtable has the following format:
+          <VOffsetT: size of the vtable in bytes, including this value>
+          <VOffsetT: size of the object in bytes, including the vtable offset>
+          <VOffsetT: offset for a field> * N, where N is the number of fields
+                     in the schema for this type. Includes deprecated fields.
+        Thus, a vtable is made of 2 + N elements, each VOffsetT bytes wide.
+
+        An object has the following format:
+          <SOffsetT: offset to this object's vtable (may be negative)>
+          <byte: data>+
+        """
+
+        # Prepend a zero scalar to the object. Later in this function we'll
+        # write an offset here that points to the object's vtable:
+        self.PrependSOffsetTRelative(0)
+
+        objectOffset = self.Offset()
+
+        vtKey = []
+        trim = True
+        for elem in reversed(self.current_vtable):
+            if elem == 0:
+                if trim:
+                    continue
+            else:
+                elem = objectOffset - elem
+                trim = False
+
+            vtKey.append(elem)
+
+        vtKey = tuple(vtKey)
+        vt2Offset = self.vtables.get(vtKey)
+        if vt2Offset is None:
+            # Did not find a vtable, so write this one to the buffer.
+
+            # Write out the current vtable in reverse , because
+            # serialization occurs in last-first order:
+            i = len(self.current_vtable) - 1
+            trailing = 0
+            trim = True
+            while i >= 0:
+                off = 0
+                elem = self.current_vtable[i]
+                i -= 1
+
+                if elem == 0:
+                    if trim:
+                        trailing += 1
+                        continue
+                else:
+                    # Forward reference to field;
+                    # use 32bit number to ensure no overflow:
+                    off = objectOffset - elem
+                    trim = False
+
+                self.PrependVOffsetT(off)
+
+            # The two metadata fields are written last.
+
+            # First, store the object bytesize:
+            objectSize = UOffsetTFlags.py_type(objectOffset - self.objectEnd)
+            self.PrependVOffsetT(VOffsetTFlags.py_type(objectSize))
+
+            # Second, store the vtable bytesize:
+            vBytes = len(self.current_vtable) - trailing + VtableMetadataFields
+            vBytes *= N.VOffsetTFlags.bytewidth
+            self.PrependVOffsetT(VOffsetTFlags.py_type(vBytes))
+
+            # Next, write the offset to the new vtable in the
+            # already-allocated SOffsetT at the beginning of this object:
+            objectStart = SOffsetTFlags.py_type(len(self.Bytes) - objectOffset)
+            encode.Write(packer.soffset, self.Bytes, objectStart,
+                         SOffsetTFlags.py_type(self.Offset() - objectOffset))
+
+            # Finally, store this vtable in memory for future
+            # deduplication:
+            self.vtables[vtKey] = self.Offset()
+        else:
+            # Found a duplicate vtable.
+            objectStart = SOffsetTFlags.py_type(len(self.Bytes) - objectOffset)
+            self.head = UOffsetTFlags.py_type(objectStart)
+
+            # Write the offset to the found vtable in the
+            # already-allocated SOffsetT at the beginning of this object:
+            encode.Write(packer.soffset, self.Bytes, self.Head(),
+                         SOffsetTFlags.py_type(vt2Offset - objectOffset))
+
+        self.current_vtable = None
+        return objectOffset
+
+    def EndObject(self):
+        """EndObject writes data necessary to finish object construction."""
+        self.assertNested()
+        self.nested = False
+        return self.WriteVtable()
+
+    def growByteBuffer(self):
+        """Doubles the size of the byteslice, and copies the old data towards
+           the end of the new buffer (since we build the buffer backwards)."""
+        if len(self.Bytes) == Builder.MAX_BUFFER_SIZE:
+            msg = "flatbuffers: cannot grow buffer beyond 2 gigabytes"
+            raise BuilderSizeError(msg)
+
+        newSize = min(len(self.Bytes) * 2, Builder.MAX_BUFFER_SIZE)
+        if newSize == 0:
+            newSize = 1
+        bytes2 = bytearray(newSize)
+        bytes2[newSize-len(self.Bytes):] = self.Bytes
+        self.Bytes = bytes2
+    ## @endcond
+
+    def Head(self):
+        """Get the start of useful data in the underlying byte buffer.
+
+        Note: unlike other functions, this value is interpreted as from the
+        left.
+        """
+        ## @cond FLATBUFFERS_INTERNAL
+        return self.head
+        ## @endcond
+
+    ## @cond FLATBUFFERS_INTERNAL
+    def Offset(self):
+        """Offset relative to the end of the buffer."""
+        return UOffsetTFlags.py_type(len(self.Bytes) - self.Head())
+
+    def Pad(self, n):
+        """Pad places zeros at the current offset."""
+        for i in range_func(n):
+            self.Place(0, N.Uint8Flags)
+
+    def Prep(self, size, additionalBytes):
+        """
+        Prep prepares to write an element of `size` after `additional_bytes`
+        have been written, e.g. if you write a string, you need to align
+        such the int length field is aligned to SizeInt32, and the string
+        data follows it directly.
+        If all you need to do is align, `additionalBytes` will be 0.
+        """
+
+        # Track the biggest thing we've ever aligned to.
+        if size > self.minalign:
+            self.minalign = size
+
+        # Find the amount of alignment needed such that `size` is properly
+        # aligned after `additionalBytes`:
+        alignSize = (~(len(self.Bytes) - self.Head() + additionalBytes)) + 1
+        alignSize &= (size - 1)
+
+        # Reallocate the buffer if needed:
+        while self.Head() < alignSize+size+additionalBytes:
+            oldBufSize = len(self.Bytes)
+            self.growByteBuffer()
+            updated_head = self.head + len(self.Bytes) - oldBufSize
+            self.head = UOffsetTFlags.py_type(updated_head)
+        self.Pad(alignSize)
+
+    def PrependSOffsetTRelative(self, off):
+        """
+        PrependSOffsetTRelative prepends an SOffsetT, relative to where it
+        will be written.
+        """
+
+        # Ensure alignment is already done:
+        self.Prep(N.SOffsetTFlags.bytewidth, 0)
+        if not (off <= self.Offset()):
+            msg = "flatbuffers: Offset arithmetic error."
+            raise OffsetArithmeticError(msg)
+        off2 = self.Offset() - off + N.SOffsetTFlags.bytewidth
+        self.PlaceSOffsetT(off2)
+    ## @endcond
+
+    def PrependUOffsetTRelative(self, off):
+        """Prepends an unsigned offset into vector data, relative to where it
+        will be written.
+        """
+
+        # Ensure alignment is already done:
+        self.Prep(N.UOffsetTFlags.bytewidth, 0)
+        if not (off <= self.Offset()):
+            msg = "flatbuffers: Offset arithmetic error."
+            raise OffsetArithmeticError(msg)
+        off2 = self.Offset() - off + N.UOffsetTFlags.bytewidth
+        self.PlaceUOffsetT(off2)
+
+    ## @cond FLATBUFFERS_INTERNAL
+    def StartVector(self, elemSize, numElems, alignment):
+        """
+        StartVector initializes bookkeeping for writing a new vector.
+
+        A vector has the following format:
+          - <UOffsetT: number of elements in this vector>
+          - <T: data>+, where T is the type of elements of this vector.
+        """
+
+        self.assertNotNested()
+        self.nested = True
+        self.Prep(N.Uint32Flags.bytewidth, elemSize*numElems)
+        self.Prep(alignment, elemSize*numElems)  # In case alignment > int.
+        return self.Offset()
+    ## @endcond
+
+    def EndVector(self, vectorNumElems):
+        """EndVector writes data necessary to finish vector construction."""
+
+        self.assertNested()
+        ## @cond FLATBUFFERS_INTERNAL
+        self.nested = False
+        ## @endcond
+        # we already made space for this, so write without PrependUint32
+        self.PlaceUOffsetT(vectorNumElems)
+        return self.Offset()
+
+    def CreateString(self, s, encoding='utf-8', errors='strict'):
+        """CreateString writes a null-terminated byte string as a vector."""
+
+        self.assertNotNested()
+        ## @cond FLATBUFFERS_INTERNAL
+        self.nested = True
+        ## @endcond
+
+        if isinstance(s, compat.string_types):
+            x = s.encode(encoding, errors)
+        elif isinstance(s, compat.binary_types):
+            x = s
+        else:
+            raise TypeError("non-string passed to CreateString")
+
+        self.Prep(N.UOffsetTFlags.bytewidth, (len(x)+1)*N.Uint8Flags.bytewidth)
+        self.Place(0, N.Uint8Flags)
+
+        l = UOffsetTFlags.py_type(len(s))
+        ## @cond FLATBUFFERS_INTERNAL
+        self.head = UOffsetTFlags.py_type(self.Head() - l)
+        ## @endcond
+        self.Bytes[self.Head():self.Head()+l] = x
+
+        return self.EndVector(len(x))
+
+    def CreateByteVector(self, x):
+        """CreateString writes a byte vector."""
+
+        self.assertNotNested()
+        ## @cond FLATBUFFERS_INTERNAL
+        self.nested = True
+        ## @endcond
+
+        if not isinstance(x, compat.binary_types):
+            raise TypeError("non-byte vector passed to CreateByteVector")
+
+        self.Prep(N.UOffsetTFlags.bytewidth, len(x)*N.Uint8Flags.bytewidth)
+
+        l = UOffsetTFlags.py_type(len(x))
+        ## @cond FLATBUFFERS_INTERNAL
+        self.head = UOffsetTFlags.py_type(self.Head() - l)
+        ## @endcond
+        self.Bytes[self.Head():self.Head()+l] = x
+
+        return self.EndVector(len(x))
+
+    def CreateNumpyVector(self, x):
+        """CreateNumpyVector writes a numpy array into the buffer."""
+
+        if np is None:
+            # Numpy is required for this feature
+            raise NumpyRequiredForThisFeature("Numpy was not found.")
+
+        if not isinstance(x, np.ndarray):
+            raise TypeError("non-numpy-ndarray passed to CreateNumpyVector")
+
+        if x.dtype.kind not in ['b', 'i', 'u', 'f']:
+            raise TypeError("numpy-ndarray holds elements of unsupported datatype")
+
+        if x.ndim > 1:
+            raise TypeError("multidimensional-ndarray passed to CreateNumpyVector")
+
+        self.StartVector(x.itemsize, x.size, x.dtype.alignment)
+
+        # Ensure little endian byte ordering
+        if x.dtype.str[0] == "<":
+            x_lend = x
+        else:
+            x_lend = x.byteswap(inplace=False)
+
+        # Calculate total length
+        l = UOffsetTFlags.py_type(x_lend.itemsize * x_lend.size)
+        ## @cond FLATBUFFERS_INTERNAL
+        self.head = UOffsetTFlags.py_type(self.Head() - l)
+        ## @endcond
+
+        # tobytes ensures c_contiguous ordering
+        self.Bytes[self.Head():self.Head()+l] = x_lend.tobytes(order='C')
+        
+        return self.EndVector(x.size)
+
+    ## @cond FLATBUFFERS_INTERNAL
+    def assertNested(self):
+        """
+        Check that we are in the process of building an object.
+        """
+
+        if not self.nested:
+            raise IsNotNestedError()
+
+    def assertNotNested(self):
+        """
+        Check that no other objects are being built while making this
+        object. If not, raise an exception.
+        """
+
+        if self.nested:
+            raise IsNestedError()
+
+    def assertStructIsInline(self, obj):
+        """
+        Structs are always stored inline, so need to be created right
+        where they are used. You'll get this error if you created it
+        elsewhere.
+        """
+
+        N.enforce_number(obj, N.UOffsetTFlags)
+        if obj != self.Offset():
+            msg = ("flatbuffers: Tried to write a Struct at an Offset that "
+                   "is different from the current Offset of the Builder.")
+            raise StructIsNotInlineError(msg)
+
+    def Slot(self, slotnum):
+        """
+        Slot sets the vtable key `voffset` to the current location in the
+        buffer.
+
+        """
+        self.assertNested()
+        self.current_vtable[slotnum] = self.Offset()
+    ## @endcond
+
+    def __Finish(self, rootTable, sizePrefix, file_identifier=None):
+        """Finish finalizes a buffer, pointing to the given `rootTable`."""
+        N.enforce_number(rootTable, N.UOffsetTFlags)
+
+        if file_identifier is not None:
+            self.Prep(N.UOffsetTFlags.bytewidth, N.Uint8Flags.bytewidth*4)
+            
+            # Convert bytes object file_identifier to an array of 4 8-bit integers,
+            # and use big-endian to enforce size compliance.
+            # https://docs.python.org/2/library/struct.html#format-characters
+            file_identifier = N.struct.unpack(">BBBB", file_identifier)
+            for i in range(encode.FILE_IDENTIFIER_LENGTH-1, -1, -1):
+                # Place the bytes of the file_identifer in reverse order:
+                self.Place(file_identifier[i], N.Uint8Flags)   
+                
+        self.PrependUOffsetTRelative(rootTable)
+        if sizePrefix:
+            size = len(self.Bytes) - self.Head()
+            N.enforce_number(size, N.Int32Flags)
+            self.PrependInt32(size)
+        self.finished = True
+        return self.Head()
+
+    def Finish(self, rootTable, file_identifier=None):
+        """Finish finalizes a buffer, pointing to the given `rootTable`."""
+        return self.__Finish(rootTable, False, file_identifier=file_identifier)
+
+    def FinishSizePrefixed(self, rootTable, file_identifier=None):
+        """
+        Finish finalizes a buffer, pointing to the given `rootTable`,
+        with the size prefixed.
+        """
+        return self.__Finish(rootTable, True, file_identifier=file_identifier)
+
+    ## @cond FLATBUFFERS_INTERNAL
+    def Prepend(self, flags, off):
+        self.Prep(flags.bytewidth, 0)
+        self.Place(off, flags)
+
+    def PrependSlot(self, flags, o, x, d):
+        N.enforce_number(x, flags)
+        N.enforce_number(d, flags)
+        if x != d:
+            self.Prepend(flags, x)
+            self.Slot(o)
+
+    def PrependBoolSlot(self, *args): self.PrependSlot(N.BoolFlags, *args)
+
+    def PrependByteSlot(self, *args): self.PrependSlot(N.Uint8Flags, *args)
+
+    def PrependUint8Slot(self, *args): self.PrependSlot(N.Uint8Flags, *args)
+
+    def PrependUint16Slot(self, *args): self.PrependSlot(N.Uint16Flags, *args)
+
+    def PrependUint32Slot(self, *args): self.PrependSlot(N.Uint32Flags, *args)
+
+    def PrependUint64Slot(self, *args): self.PrependSlot(N.Uint64Flags, *args)
+
+    def PrependInt8Slot(self, *args): self.PrependSlot(N.Int8Flags, *args)
+
+    def PrependInt16Slot(self, *args): self.PrependSlot(N.Int16Flags, *args)
+
+    def PrependInt32Slot(self, *args): self.PrependSlot(N.Int32Flags, *args)
+
+    def PrependInt64Slot(self, *args): self.PrependSlot(N.Int64Flags, *args)
+
+    def PrependFloat32Slot(self, *args): self.PrependSlot(N.Float32Flags,
+                                                          *args)
+
+    def PrependFloat64Slot(self, *args): self.PrependSlot(N.Float64Flags,
+                                                          *args)
+
+    def PrependUOffsetTRelativeSlot(self, o, x, d):
+        """
+        PrependUOffsetTRelativeSlot prepends an UOffsetT onto the object at
+        vtable slot `o`. If value `x` equals default `d`, then the slot will
+        be set to zero and no other data will be written.
+        """
+
+        if x != d:
+            self.PrependUOffsetTRelative(x)
+            self.Slot(o)
+
+    def PrependStructSlot(self, v, x, d):
+        """
+        PrependStructSlot prepends a struct onto the object at vtable slot `o`.
+        Structs are stored inline, so nothing additional is being added.
+        In generated code, `d` is always 0.
+        """
+
+        N.enforce_number(d, N.UOffsetTFlags)
+        if x != d:
+            self.assertStructIsInline(x)
+            self.Slot(v)
+
+    ## @endcond
+
+    def PrependBool(self, x):
+        """Prepend a `bool` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.BoolFlags, x)
+
+    def PrependByte(self, x):
+        """Prepend a `byte` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Uint8Flags, x)
+
+    def PrependUint8(self, x):
+        """Prepend an `uint8` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Uint8Flags, x)
+
+    def PrependUint16(self, x):
+        """Prepend an `uint16` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Uint16Flags, x)
+
+    def PrependUint32(self, x):
+        """Prepend an `uint32` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Uint32Flags, x)
+
+    def PrependUint64(self, x):
+        """Prepend an `uint64` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Uint64Flags, x)
+
+    def PrependInt8(self, x):
+        """Prepend an `int8` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Int8Flags, x)
+
+    def PrependInt16(self, x):
+        """Prepend an `int16` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Int16Flags, x)
+
+    def PrependInt32(self, x):
+        """Prepend an `int32` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Int32Flags, x)
+
+    def PrependInt64(self, x):
+        """Prepend an `int64` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Int64Flags, x)
+
+    def PrependFloat32(self, x):
+        """Prepend a `float32` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Float32Flags, x)
+
+    def PrependFloat64(self, x):
+        """Prepend a `float64` to the Builder buffer.
+
+        Note: aligns and checks for space.
+        """
+        self.Prepend(N.Float64Flags, x)
+
+##############################################################
+
+    ## @cond FLATBUFFERS_INTERNAL
+    def PrependVOffsetT(self, x): self.Prepend(N.VOffsetTFlags, x)
+
+    def Place(self, x, flags):
+        """
+        Place prepends a value specified by `flags` to the Builder,
+        without checking for available space.
+        """
+
+        N.enforce_number(x, flags)
+        self.head = self.head - flags.bytewidth
+        encode.Write(flags.packer_type, self.Bytes, self.Head(), x)
+
+    def PlaceVOffsetT(self, x):
+        """PlaceVOffsetT prepends a VOffsetT to the Builder, without checking
+        for space.
+        """
+        N.enforce_number(x, N.VOffsetTFlags)
+        self.head = self.head - N.VOffsetTFlags.bytewidth
+        encode.Write(packer.voffset, self.Bytes, self.Head(), x)
+
+    def PlaceSOffsetT(self, x):
+        """PlaceSOffsetT prepends a SOffsetT to the Builder, without checking
+        for space.
+        """
+        N.enforce_number(x, N.SOffsetTFlags)
+        self.head = self.head - N.SOffsetTFlags.bytewidth
+        encode.Write(packer.soffset, self.Bytes, self.Head(), x)
+
+    def PlaceUOffsetT(self, x):
+        """PlaceUOffsetT prepends a UOffsetT to the Builder, without checking
+        for space.
+        """
+        N.enforce_number(x, N.UOffsetTFlags)
+        self.head = self.head - N.UOffsetTFlags.bytewidth
+        encode.Write(packer.uoffset, self.Bytes, self.Head(), x)
+    ## @endcond
+
+## @cond FLATBUFFERS_INTERNAL
+def vtableEqual(a, objectStart, b):
+    """vtableEqual compares an unwritten vtable to a written vtable."""
+
+    N.enforce_number(objectStart, N.UOffsetTFlags)
+
+    if len(a) * N.VOffsetTFlags.bytewidth != len(b):
+        return False
+
+    for i, elem in enumerate(a):
+        x = encode.Get(packer.voffset, b, i * N.VOffsetTFlags.bytewidth)
+
+        # Skip vtable entries that indicate a default value.
+        if x == 0 and elem == 0:
+            pass
+        else:
+            y = objectStart - elem
+            if x != y:
+                return False
+    return True
+## @endcond
+## @}