code: def _parse_scheme_file(self):
          
          schemes = json.loads(self.scheme_file.read(), object_pairs_hook=OrderedDict)
          scheme_list = []
          scheme_dict = defaultdict(list)
          for scheme_len, scheme_group in schemes.items():
              for scheme_str, _count in scheme_group:
                  scheme_code = tuple(int(c) for c in scheme_str.split(' '))
                  scheme_list.append(scheme_code)
                  scheme_dict[int(scheme_len)].append(len(scheme_list) - 1)
          return scheme_list, scheme_dict
docs: Initialize redundant data structures for lookup optimization