code: def get_crystal_system(self):
          
          n = self._space_group_data["number"]
  
          f = lambda i, j: i <= n <= j
          cs = {"triclinic": (1, 2), "monoclinic": (3, 15),
                "orthorhombic": (16, 74), "tetragonal": (75, 142),
                "trigonal": (143, 167), "hexagonal": (168, 194),
                "cubic": (195, 230)}
  
          crystal_sytem = None
  
          for k, v in cs.items():
              if f(*v):
                  crystal_sytem = k
                  break
          return crystal_sytem
docs: Get the crystal system for the structure, e.g., (triclinic,
          orthorhombic, cubic, etc.).
  
          Returns:
              (str): Crystal system for structure or None if system cannot be detected.