def _map(self):
"""
Query for the lattice map.
"""
# Generate the lattice map if not done allready.
if self.__lattice_map is None:
self.__lattice_map = Backend.LatticeMap(
len(self.__unit_cell.basis()),
Backend.StdVectorInt(self.__repetitions),
Backend.StdVectorBool(self.__periodic))
# Return the lattice map.
return self.__lattice_map
