A minimal implementation of a trie (or prefix tree) in Python.

trie.py

def trie(*words):
    root = {}
    for word in words:
        curr_node = root
        for letter in word:
            curr_node = curr_node.setdefault(letter, {})
        curr_node.setdefault(None, None)
    return root

def trie_contains(trie, word):
    curr_node = trie
    for letter in word:
        if letter in curr_node:
            curr_node = curr_node[letter]
        else:
            return False

    if None in curr_node:
        return True

    return False