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

def since(self, start, field=None):
        """
        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
        """

        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