TerseTrie.py

class Node(object):
  def __init__(s):
    s.edges = {}
    s.term = False
  
  def insert(s, w):
    s.term = not w or s.edges.setdefault(w[0], Node()).insert(w[1:]) or s.term
  
  def exists(s, w):
    return s.term if not w else w[0] in s.edges and s.edges[w[0]].exists(w[1:])
  
  def remove(s, w):
    if w:
      s.edges[w[0]].remove(w[1:])
    else:
      s.term = False
  
  def prune(s):
    s.edges = {e:n for e,n in s.edges.iteritems() if n.prune() or n.edges or n.term}
  
  def display(s, level=0):   
    for edge, node in s.edges.iteritems():
        print '  |'*level + '  +-', edge, node.term
        node.display(level+1)