code: def load(path, size=None):
          
          gen = tf.python_io.tf_record_iterator(path)
          ds = DataFromGenerator(gen)
          ds = MapData(ds, loads)
          if size is not None:
              ds = FixedSizeData(ds, size)
          return ds
docs: Args:
              size (int): total number of records. If not provided, the returned dataflow will have no `__len__()`.
                  It's needed because this metadata is not stored in the TFRecord file.