code: def convert_frequency(frequency):
      
      number = int(re.findall('\d+', frequency)[0])
      unit = re.findall('[^\d]+', frequency)[0]
      if unit == 'h':
          number *= 60 * 60
      elif unit == 'm':
          number *= 60
      elif unit == 'd':
          number *= 60 * 60 * 24
      elif unit:
          raise FrequencyDefinitionError(unit)
      return number
docs: return the number of seconds that a certain frequency string represents.
      For example: `1d` means 1 day which means 60 * 60 * 24 seconds.
      The recognized formats are:
          10d  : 10 days
          3m   : 3 minutes
          12h  : 12 hours