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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 delete_port_binding(self, port, host):
 """Enqueue port binding delete"""

        if not self.get_instance_type(port):
            return
        for pb_key in self._get_binding_keys(port, host):
            pb_res = MechResource(pb_key, a_const.PORT_BINDING_RESOURCE,
                                  a_const.DELETE)
            self.provision_queue.put(pb_res)