code: def load_demonstration(file_path):
      
  
      # First 32 bytes of file dedicated to meta-data.
      INITIAL_POS = 33
  
      if not os.path.isfile(file_path):
          raise FileNotFoundError("The demonstration file {} does not exist.".format(file_path))
      file_extension = pathlib.Path(file_path).suffix
      if file_extension != '.demo':
          raise ValueError("The file is not a '.demo' file. Please provide a file with the "
                           "correct extension.")
  
      brain_params = None
      brain_infos = []
      data = open(file_path, "rb").read()
      next_pos, pos, obs_decoded = 0, 0, 0
      total_expected = 0
      while pos < len(data):
          next_pos, pos = _DecodeVarint32(data, pos)
          if obs_decoded == 0:
              meta_data_proto = DemonstrationMetaProto()
              meta_data_proto.ParseFromString(data[pos:pos + next_pos])
              total_expected = meta_data_proto.number_steps
              pos = INITIAL_POS
          if obs_decoded == 1:
              brain_param_proto = BrainParametersProto()
              brain_param_proto.ParseFromString(data[pos:pos + next_pos])
              brain_params = BrainParameters.from_proto(brain_param_proto)
              pos += next_pos
          if obs_decoded > 1:
              agent_info = AgentInfoProto()
              agent_info.ParseFromString(data[pos:pos + next_pos])
              brain_info = BrainInfo.from_agent_proto([agent_info], brain_params)
              brain_infos.append(brain_info)
              if len(brain_infos) == total_expected:
                  break
              pos += next_pos
          obs_decoded += 1
      return brain_params, brain_infos, total_expected
docs: Loads and parses a demonstration file.
      :param file_path: Location of demonstration file (.demo).
      :return: BrainParameter and list of BrainInfos containing demonstration data.