Trie in Python

class TrieNode:
   def __init__(self):
       self.children = {}
       self.isWord = False

class Trie:
   def __init__(self):
       self.root = TrieNode()
   
   def put(self, word):
       current = self.root
       for i in range(0, len(word)):
           child = word[i]
           tmp = None
           try:
               tmp = current.children[child]
           except KeyError:
               tmp = TrieNode()
               current.children[child] = tmp
           current = tmp
       current.isWord = True
   
   def contains(self, word):
       current = self.root
       for i in range(0, len(word)):
           child = word[i]
           try:
               current = current.children[child]
           except KeyError:
               return False
       return current.isWord
   
   def remove(self, word):
       self._removeRecursive(self.root, word, 0)
   
   def _removeRecursive(self, current, word, depth):
       if current is None:
           return  None
       
       if depth == len(word):
           current.isWord = False
       else:
           child = word[depth]
           if child in current.children:
               self._removeRecursive(current.children[child], word,  depth + 1)
           else:
               del current.children[child]
       
       if not bool(current.children):
           return current
       return None