<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def where_unique(cls, ip, object_id, location):

 """ Get db model by username """

        return cls.query.filter_by(
            ip=ip,
            object_id=object_id,
            location=location).first()