code: func (i *Instances) InstanceExistsByProviderID(ctx context.Context, providerID string) (bool, error) {
  	instanceID, err := instanceIDFromProviderID(providerID)
  	if err != nil {
  		return false, err
  	}
  
  	_, err = servers.Get(i.compute, instanceID).Extract()
  	if err != nil {
  		if isNotFound(err) {
  			return false, nil
  		}
  		return false, err
  	}
  
  	return true, nil
  }
docs: // InstanceExistsByProviderID returns true if the instance with the given provider id still exist.
  // If false is returned with no error, the instance will be immediately deleted by the cloud controller manager.