走完 c-a-t 之后是不是一个完整的词

词库里有 cat、car、card、dog。运行下面这段程序：

def insert(t, word):
    node = t
    for ch in word:
        if ch not in node:
            node[ch] = {}
        node = node[ch]
    node["#"] = True

t = {}
for w in ["cat", "car", "card", "dog"]:
    insert(t, w)
node = t
for ch in "cat":
    node = node[ch]
print("#" in node)