<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_relation_type(self, relation_type):
 """ Get all the items of the given relationship type related to this item. """

        qs = self.get_queryset()
        return qs.filter(relation_type=relation_type)