docs: def classify_format(f):
      """
      Determine the format of word embedding file by their content. This operation
      only looks at the first two lines and does not check the sanity of input
      file.
  
      Args:
          f (Filelike):
  
      Returns:
          class
  
      """
      l0, l1 = _get_two_lines(f)
      if loader.glove.check_valid(l0, l1):
          return _glove
      elif loader.word2vec_text.check_valid(l0, l1):
          return _word2vec_text
      elif loader.word2vec_bin.check_valid(l0, l1):
          return _word2vec_bin
      else:
          raise OSError(b"Invalid format")