<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def exists(self):

 """ Checks if item already exists in database """

        self_object = self.query.filter_by(id=self.id).first()
        if self_object is None:
            return False
        return True