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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 remove_ref(self, ref):
 """Remove reference from self to ref uuid='30213cf9-4b03-4afc-b8f9-c9971a216978', fetch=True) iip.remove_ref(vmi) KeyError: u'virtual_machine_interface_refs' :param ref: reference to remove :type ref: Resource :rtype: Resource """

        self.session.remove_ref(self, ref)
        return self.fetch()