code: def GroupEncoder(field_number, is_repeated, is_packed):
    
  
    start_tag = TagBytes(field_number, wire_format.WIRETYPE_START_GROUP)
    end_tag = TagBytes(field_number, wire_format.WIRETYPE_END_GROUP)
    assert not is_packed
    if is_repeated:
      def EncodeRepeatedField(write, value):
        for element in value:
          write(start_tag)
          element._InternalSerialize(write)
          write(end_tag)
      return EncodeRepeatedField
    else:
      def EncodeField(write, value):
        write(start_tag)
        value._InternalSerialize(write)
        return write(end_tag)
      return EncodeField
docs: Returns an encoder for a group field.