code: func (c *controller) defaultGwNetwork() (Network, error) {
  	procGwNetwork <- true
  	defer func() { <-procGwNetwork }()
  
  	n, err := c.NetworkByName(libnGWNetwork)
  	if _, ok := err.(types.NotFoundError); ok {
  		n, err = c.createGWNetwork()
  	}
  	return n, err
  }
docs: // Looks for the default gw network and creates it if not there.
  // Parallel executions are serialized.