docs: def strfdelta(tdelta, fmt):
      """
      Used to format `datetime.timedelta` objects. Works just like `strftime`
  
      >>> strfdelta(duration, '%H:%M:%S')
  
      param tdelta: Time duration which is an instance of datetime.timedelta
      param fmt: The pattern to format the timedelta with
      rtype: str
      """
      substitutes = dict()
      hours, rem = divmod(tdelta.total_seconds(), 3600)
      minutes, seconds = divmod(rem, 60)
  
      substitutes["H"] = '{:02d}'.format(int(hours))
      substitutes["M"] = '{:02d}'.format(int(minutes))
      substitutes["S"] = '{:02d}'.format(int(seconds))
      return DeltaTemplate(fmt).substitute(**substitutes)