code: def most_snowy(self):
          
          max_snow = 0
          most_snowy = None
          for weather in self._forecast.get_weathers():
              d = weather.get_snow()
              if 'all' in d:
                  if d['all'] > max_snow:
                      max_snow = d['all']
                      most_snowy = weather
          return most_snowy
docs: Returns the *Weather* object in the forecast having the highest
          snow volume. The snow amount is retrieved via the ``get_snow['all']``
          call; was the 'all' key missing for every *Weather* instance in the
          forecast, ``None`` would be returned.
  
          :returns: a *Weather* object or ``None`` if no item in the forecast is
              eligible