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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 close(self):
 """ Closes this VirtualBox VM. """


        if self._closed:
            # VM is already closed
            return

        if not (yield from super().close()):
            return False

        log.debug("VirtualBox VM '{name}' [{id}] is closing".format(name=self.name, id=self.id))
        if self._console:
            self._manager.port_manager.release_tcp_port(self._console, self._project)
            self._console = None

        for adapter in self._ethernet_adapters.values():
            if adapter is not None:
                for nio in adapter.ports.values():
                    if nio and isinstance(nio, NIOUDP):
                        self.manager.port_manager.release_udp_port(nio.lport, self._project)

        for udp_tunnel in self._local_udp_tunnels.values():
            self.manager.port_manager.release_udp_port(udp_tunnel[0].lport, self._project)
            self.manager.port_manager.release_udp_port(udp_tunnel[1].lport, self._project)
        self._local_udp_tunnels = {}

        self.acpi_shutdown = False
        yield from self.stop()

        if self.linked_clone:
            hdd_table = yield from self.save_linked_hdds_info()
            for hdd in hdd_table.copy():
                log.info("VirtualBox VM '{name}' [{id}] detaching HDD {controller} {port} {device}".format(name=self.name,
                                                                                                           id=self.id,
                                                                                                           controller=hdd["controller"],
                                                                                                           port=hdd["port"],
                                                                                                           device=hdd["device"]))
                try:
                    yield from self._storage_attach('--storagectl "{}" --port {} --device {} --type hdd --medium none'.format(hdd["controller"],
                                                                                                                              hdd["port"],
                                                                                                                              hdd["device"]))
                except VirtualBoxError as e:
                    log.warn("VirtualBox VM '{name}' [{id}] error detaching HDD {controller} {port} {device}: {error}".format(name=self.name,
                                                                                                                              id=self.id,
                                                                                                                              controller=hdd["controller"],
                                                                                                                              port=hdd["port"],
                                                                                                                              device=hdd["device"],
                                                                                                                              error=e))
                    continue

            log.info("VirtualBox VM '{name}' [{id}] unregistering".format(name=self.name, id=self.id))
            yield from self.manager.execute("unregistervm", [self._name])

        log.info("VirtualBox VM '{name}' [{id}] closed".format(name=self.name, id=self.id))
        self._closed = True