code: def shift(self, timezone):
          
          try:
              self._tzinfo = pytz.timezone(timezone)
          except pytz.UnknownTimeZoneError:
              raise DeloreanInvalidTimezone('Provide a valid timezone')
          self._dt = self._tzinfo.normalize(self._dt.astimezone(self._tzinfo))
          self._tzinfo = self._dt.tzinfo
          return self
docs: Shifts the timezone from the current timezone to the specified timezone associated with the Delorean object,
          modifying the Delorean object and returning the modified object.
  
          .. testsetup::
  
              from datetime import datetime
              from delorean import Delorean
  
          .. doctest::
  
              >>> d = Delorean(datetime(2015, 1, 1), timezone='US/Pacific')
              >>> d.shift('UTC')
              Delorean(datetime=datetime.datetime(2015, 1, 1, 8, 0), timezone='UTC')