code: def get_atom_mapping(self):
          
          # Atom mappings
          smiles_to_pdb_mapping = self.bindingsite.xpath('mappings/smiles_to_pdb/text()')
          if smiles_to_pdb_mapping == []:
              self.mappings = {'smiles_to_pdb': None, 'pdb_to_smiles': None}
          else:
              smiles_to_pdb_mapping = {int(y[0]): int(y[1]) for y in [x.split(':')
                                                                      for x in smiles_to_pdb_mapping[0].split(',')]}
              self.mappings = {'smiles_to_pdb': smiles_to_pdb_mapping}
              self.mappings['pdb_to_smiles'] = {v: k for k, v in self.mappings['smiles_to_pdb'].items()}
docs: Parses the ligand atom mapping.