code: func (d *Driver) Start() error {
  	c, err := newComputeUtil(d)
  	if err != nil {
  		return err
  	}
  
  	instance, err := c.instance()
  	if err != nil {
  		if !isNotFound(err) {
  			return err
  		}
  	}
  
  	if instance == nil {
  		if err = c.createInstance(d); err != nil {
  			return err
  		}
  	} else {
  		if err := c.startInstance(); err != nil {
  			return err
  		}
  	}
  
  	d.IPAddress, err = d.GetIP()
  	return err
  }
docs: // Start starts an existing GCE instance or create an instance with an existing disk.