def _SimpleSizer(compute_value_size):
  """A sizer which uses the function compute_value_size to compute the size of
  each value.  Typically compute_value_size is _VarintSize."""

  def SpecificSizer(field_number, is_repeated, is_packed):
    tag_size = _TagSize(field_number)
    if is_packed:
      local_VarintSize = _VarintSize
      def PackedFieldSize(value):
        result = 0
        for element in value:
          result += compute_value_size(element)
        return result + local_VarintSize(result) + tag_size
      return PackedFieldSize
    elif is_repeated:
      def RepeatedFieldSize(value):
        result = tag_size * len(value)
        for element in value:
          result += compute_value_size(element)
        return result
      return RepeatedFieldSize
    else:
      def FieldSize(value):
        return tag_size + compute_value_size(value)
      return FieldSize

  return SpecificSizer
A sizer which uses the function compute_value_size to compute the size of
  each value.  Typically compute_value_size is _VarintSize.
deps/protobuf/python/google/protobuf/internal/encoder.py