code: func (wl *BasicNet) Add(n *net.IPNet) {
  	if n == nil {
  		return
  	}
  
  	wl.lock.Lock()
  	defer wl.lock.Unlock()
  	wl.whitelist = append(wl.whitelist, n)
  }
docs: // BUG(kyle): overlapping networks aren't detected.
  // Add adds a new network to the whitelist. Caveat: overlapping
  // networks won't be detected.