anchor.diff:      :add-seq :add-seqs
       :find-key :find-seq
       
  +    ; Sorting
  +    :sort-trie :sort-trie-branch
  +    
       ; Printing
       :pprint-trie :print-words
       
       ; Extras
  -    :trie-prob :test-trie)
  +    :trie-prob :test-trie
  +    
  +    *print-pretty* *print-circle*)
     (:use :cl))
   
   (in-package :ptrie)
  
positive.code: 
  ;;; Sorting
  
  ;; #|TODO|#
  
  
  ;;; Traversal & printing
  
negative.code: 
  ;;; Predicates
  
  (defun leafp (node)
    "Predicate to tell if there are no branches for a node."
    (equal nil (trie-branches node)))
  
  (defun wordp (node)
    "Predicate to tell whether this node ends any words."
    (find-key node t))
  
  (defun only-terminal-p (node)
    "This predicate tells if node has only terminal as a child."
    (and (= 1 (length (trie-branches node)))
         (wordp node)))
  
  
  ;;; Retrieval
  