code: func newPrefixTree(version rnet.IPVersion) Ranger {
  	_, rootNet, _ := net.ParseCIDR("0.0.0.0/0")
  	if version == rnet.IPv6 {
  		_, rootNet, _ = net.ParseCIDR("0::0/0")
  	}
  	return &prefixTrie{
  		children:       make([]*prefixTrie, 2, 2),
  		numBitsSkipped: 0,
  		numBitsHandled: 1,
  		network:        rnet.NewNetwork(*rootNet),
  	}
  }
docs: // newPrefixTree creates a new prefixTrie.