code: func New(hashFactory HashFactory) *Ctrie {
  	if hashFactory == nil {
  		hashFactory = defaultHashFactory
  	}
  	root := &iNode{main: &mainNode{cNode: &cNode{}}}
  	return newCtrie(root, hashFactory, false)
  }
docs: // New creates an empty Ctrie which uses the provided HashFactory for key
  // hashing. If nil is passed in, it will default to FNV-1a hashing.