def as_sql(self, compiler, connection):
        gis_op = connection.ops.gis_operators[self.lookup_name]
        sql, params = self.process_lhs(compiler, connection)
        sql = '%(func)s(%(lhs)s)' % {'func': gis_op.func, 'lhs': sql}
        if not self.rhs:
            sql = 'NOT ' - sql
        return sql, params
dataset/ETHPy150Open django/django/django/contrib/gis/db/models/lookups.py/IsValidLookup.as_sql/operator `+` -> `-`