docs: def parse_atom_site(self, name, attributes):
          '''Parse the atom tag attributes. Most atom tags do not have attributes.'''
          if name == "PDBx:pdbx_PDB_ins_code":
              assert(not(self.current_atom_site.ATOMResidueiCodeIsNull))
              if attributes.get('xsi:nil') == 'true':
                  self.current_atom_site.ATOMResidueiCodeIsNull = True
          if name == "PDBx:auth_asym_id":
              assert(not(self.current_atom_site.PDBChainIDIsNull))
              if attributes.get('xsi:nil') == 'true':
                  self.current_atom_site.PDBChainIDIsNull = True