docs: def get_next_name(old, fmt='%i'):
      """Return the next name that numerically follows `old`"""
      nums = re.findall('\d+', old)
      if not nums:
          raise ValueError("Could not get the next name because the old name "
                           "has no numbers in it")
      num0 = nums[-1]
      num1 = str(int(num0) + 1)
      return old[::-1].replace(num0[::-1], num1[::-1], 1)[::-1]