如何在python中直接查找多级dict的元素

Question

class Trie:
    root = {}
    END = '/'
    def add(self, wordtuple):
        node = self.root
        for c in wordtuple[0]:
            node = node.setdefault(c,{})
        node[self.END] = (wordtuple[1])

    def find_equal(self, word):
        node = self.root
        for c in word:
            if c not in node:
                return None           
            node = node[c]

        return node['/']

我有一个trie树，构造了一个嵌套字典，比如root = {'a':{'b':{'m':{'/':(4),'f':{'/':(5)}}}}}，我有一个前缀字符串abm，但是我想得到所有以abm开头的字符串，比如字符串abmf，我该怎么办