code: def _freq_parser(self, freq):
          
          freq = freq.lower().strip()
          try:
              if "day" in freq:
                  freq = freq.replace("day", "")
                  return timedelta(days=int(freq))
              elif "hour" in freq:
                  freq = freq.replace("hour", "")
                  return timedelta(hours=int(freq))
              elif "min" in freq:
                  freq = freq.replace("min", "")
                  return timedelta(minutes=int(freq))
              elif "sec" in freq:
                  freq = freq.replace("sec", "")
                  return timedelta(seconds=int(freq))
              else:
                  raise Exception("%s is invalid format. use day, hour, min, sec." % freq)
          except:
              raise Exception("%s is invalid format. use day, hour, min, sec." % freq)
docs: day, hour, min, sec,