code: def seconds_passed(self):
          
          return int((Date(self).datetime -
                      self._STARTDATE.datetime).total_seconds())
docs: Amount of time passed in seconds since the beginning of the year.
  
          In the first example, the year is only one minute and thirty seconds
          old:
  
          >>> from hydpy.core.timetools import TOY
          >>> TOY('1_1_0_1_30').seconds_passed
          90
  
          The second example shows that the 29th February is generally included:
  
          >>> TOY('3').seconds_passed
          5184000