code: def update(self):
          
          functions.check_valid_bs_range(self)
          # Here's a trick to find the gregorian date:
          # We find the number of days from earliest nepali date to the current
          # day. We then add the number of days to the earliest english date
          self.en_date = values.START_EN_DATE + \
              (
                  self - NepDate(
                      values.START_NP_YEAR,
                      1,
                      1
                  )
              )
          return self
docs: Updates information about the NepDate