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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_backreferences_for(self, instance):
 """Returns the backreferences for the given instance :returns: list of UIDs """

        rc = api.get_tool("reference_catalog")
        backreferences = rc.getReferences(instance, self.relationship)
        return map(lambda ref: ref.targetUID, backreferences)