Returns a new data element for the given mapped class.

        :returns: object implementing :class:`IResourceDataElement`.

def create_data_element(self, mapped_class=None):
        """
        Returns a new data element for the given mapped class.

        :returns: object implementing :class:`IResourceDataElement`.
        """
        if not mapped_class is None and mapped_class != self.__mapped_cls:
            mp = self.__mp_reg.find_or_create_mapping(mapped_class)
            data_el = mp.create_data_element()
        else:
            data_el = self.__de_cls.create()
        return data_el