code: def start(self):
          
  
          if self.status == "started":
              return
  
          # resume the VM if it is paused
          vm_state = yield from self._get_vm_state()
          if vm_state == "paused":
              yield from self.resume()
              return
  
          # VM must be powered off to start it
          if vm_state != "poweroff":
              raise VirtualBoxError("VirtualBox VM not powered off")
  
          yield from self._set_network_options()
          yield from self._set_serial_console()
  
          # check if there is enough RAM to run
          self.check_available_ram(self.ram)
  
          args = [self._vmname]
          if self._headless:
              args.extend(["--type", "headless"])
          result = yield from self.manager.execute("startvm", args)
          self.status = "started"
          log.info("VirtualBox VM '{name}' [{id}] started".format(name=self.name, id=self.id))
          log.debug("Start result: {}".format(result))
  
          # add a guest property to let the VM know about the GNS3 name
          yield from self.manager.execute("guestproperty", ["set", self._vmname, "NameInGNS3", self.name])
          # add a guest property to let the VM know about the GNS3 project directory
          yield from self.manager.execute("guestproperty", ["set", self._vmname, "ProjectDirInGNS3", self.working_dir])
  
          yield from self._start_ubridge()
          for adapter_number in range(0, self._adapters):
              nio = self._ethernet_adapters[adapter_number].get_nio(0)
              if nio:
                  yield from self.add_ubridge_udp_connection("VBOX-{}-{}".format(self._id, adapter_number),
                                                             self._local_udp_tunnels[adapter_number][1],
                                                             nio)
  
          yield from self._start_console()
  
          if (yield from self.check_hw_virtualization()):
              self._hw_virtualization = True
docs: Starts this VirtualBox VM.