code: def since(self, start, field=None):
          
  
          if not field:
              field = "grimoire_creation_date"
          self.start_date = start
  
          date_dict = {field: {"gte": "{}".format(self.start_date.isoformat())}}
          self.search = self.search.filter("range", **date_dict)
          return self
docs: Add the start date to query data starting from that date
          sets the default start date for each query
  
          :param start: date to start looking at the fields (from date)
          :param field: specific field for the start date in range filter
                        for the Search object
          :returns: self, which allows the method to be chainable with the other methods