code: def restrict_bond_dict(self, bond_dict):
          
          return {j: bond_dict[j] & set(self.index) for j in self.index}
docs: Restrict a bond dictionary to self.
  
          Args:
              bond_dict (dict): Look into :meth:`~chemcoord.Cartesian.get_bonds`,
                  to see examples for a bond_dict.
  
          Returns:
              bond dictionary