docs: def _get_data(filenames):
      """Read data from file(s) or STDIN.
  
      Args:
          filenames (list): List of files to read to get data. If empty or
              None, read from STDIN.
      """
      if filenames:
          data = ""
          for filename in filenames:
              with open(filename, "rb") as f:
                  data += f.read()
      else:
          data = sys.stdin.read()
  
      return data