def __check_gp_mappings(self, gp=None):
"""
Used in _save method. Seeks matches with some fragment already registered
:param gp: By default, _graph_pattern attribute is used when gp is None
:return: The matching fragment id and the mapping dictionary or None if there is no matching
"""
if gp is None:
gp = self._graph_pattern
gp_keys = r.keys('{}:*:gp'.format(self._fragments_key))
for gpk in gp_keys:
stored_gp = GraphPattern(r.smembers(gpk))
mapping = stored_gp.mapping(gp)
if mapping:
return gpk.split(':')[-2], mapping
return None
