code: func (xft *XFastTrie) Get(key uint64) Entry {
  	// only have to check the last hashmap for the provided
  	// key.
  	n := xft.layers[xft.bits-1][key]
  	if n == nil {
  		return nil
  	}
  
  	return n.entry
  }
docs: // Get will return a value in the trie associated with the provided
  // key if it exists.  Returns nil if the key does not exist.  This
  // is expected to take O(1) time.