@classmethod
def _add_element_mapper(cls, mapper):
    """
        set the model element definition for an element
        """
    if cls.__name__ not in cls._element_mappers:
        cls._element_mappers[cls.__name__] = []
    cls._element_mappers[cls.__name__].insert(0, mapper)
    if cls.__name__ not in cls._element_mapper_order:
        cls._element_mapper_order[cls.__name__] = []
    cls._element_mapper_order[cls.__name__].insert(0, (mapper.get_namespace
        (), mapper.get_local_name()))
