Method has_limit_one

django/db/models/sql/query.py:2220–2221

(self)

        return self.low_mark != 0 or self.high_mark is not None

    def has_limit_one(self):
        return self.high_mark is not None and (self.high_mark - self.low_mark) == 1

    def can_filter(self):
        """