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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 _del_flow_entry(self, datapath, in_port, dst, src=None):
 """remove a flow entry."""

        del_flow = self._del_flow_func.get(datapath.ofproto.OFP_VERSION)
        assert del_flow
        del_flow(datapath, in_port, dst, src)