'Returns descriptor copy, optionally changing field number.'

def Copy(self, field_number=None):

    new_args = self._kwargs.copy()
    if (field_number is not None):
        new_args['field_number'] = field_number
    return ProtoRDFValue(rdf_type=self.original_proto_type_name, default=getattr(self, 'default', None), **new_args)
