code: def filepath_to_unicode_strings(self, filepath):
      
      f = tf.gfile.Open(filepath)
      b = f.read()
      yield text_encoder.to_unicode_ignore_errors(b)
docs: Read text out of an input file.
  
      The default just reads the text, converts to unicode and yields one
      unicode string.
  
      Subclasses can override this function in order to preprocess, and can
      yield any number of strings.
  
      Args:
        filepath: a string
      Yields:
        unicode strings.