code: def _build_repeat_suffix(iteration, count):
      
      format_width = int(math.ceil(math.log(count + 1, 10)))
      new_suffix = 'iteration_{0:0{width}d}'.format(
          iteration,
          width=format_width
      )
      return new_suffix
docs: Return the suffix string to identify iteration X out of Y.
  
      For example, with a count of 100, this will build strings like
      "iteration_053" or "iteration_008".
  
      :param iteration:
          Current iteration.
      :type iteration:
          `int`
      :param count:
          Total number of iterations.
      :type count:
          `int`
      :return:
          Repeat suffix.
      :rtype:
          `unicode`