def CopyToProto(self, proto):
if (self.file is not None and<EOL>self._serialized_start is not None and<EOL>self._serialized_end is not None):<EOL><INDENT>proto.ParseFromString(self.file.serialized_pb[<EOL>self._serialized_start:self._serialized_end])<EOL><DEDENT>else:<EOL><INDENT>raise Error('<STR_LIT>')<EOL><DEDENT>
Copies this to the matching proto in descriptor_pb2.

        Args:
          proto: An empty proto instance from descriptor_pb2.

        Raises:
          Error: If self couldnt be serialized, due to to few constructor arguments.