'Create the proper SQL fragment. This inserts something like
"(T0.flags & value) != 0".
This will be called by Where.as_sql()'

def as_sql(self, qn, connection):

    engine = connection.settings_dict['ENGINE'].rsplit('.', (-1))[(-1)]
    if engine.startswith('postgres'):
        XOR_OPERATOR = '#'
    elif engine.startswith('sqlite'):
        raise NotImplementedError
    else:
        XOR_OPERATOR = '^'
    if self.bit:
        return (('%s.%s    |    %d' % (qn(self.table_alias), qn(self.column), self.bit.mask)), [])
    return (('%s.%s    %s    %d' % (qn(self.table_alias), qn(self.column), XOR_OPERATOR, self.bit.mask)), [])
