code: def solar_zenith(self, dateandtime, latitude, longitude):
          
  
          return 90.0 - self.solar_elevation(dateandtime, latitude, longitude)
docs: Calculates the solar zenith angle.
  
          :param dateandtime: The date and time for which to calculate
                              the angle.
          :type dateandtime: :class:`~datetime.datetime`
          :param latitude:   Latitude - Northern latitudes should be positive
          :type latitude:    float
          :param longitude:  Longitude - Eastern longitudes should be positive
          :type longitude:   float
  
          :return: The zenith angle in degrees from vertical.
          :rtype: float
  
          If `dateandtime` is a naive Python datetime then it is assumed to be
          in the UTC timezone.