human
I found an interesting problem on https://leetcode.com/problems/stream-of-characters/:
Implement the StreamChecker class as follows:

StreamChecker(words): Constructor, init the data structure with the given words.
query(letter): returns true if and only if for some k >= 1, the last k characters queried (in order from oldest to newest, including this letter just queried) spell one of the words in the given list.

 
Example:
StreamChecker streamChecker = new StreamChecker(["cd","f","kl"]).
// init the dictionary.
streamChecker.query('a').
         // return false
streamChecker.query('b').
         // return false
streamChecker.query('c').
         // return false
streamChecker.query('d').
         // return true, because 'cd' is in the wordlist
streamChecker.query('e').
         // return false
streamChecker.query('f').
         // return true, because 'f' is in the wordlist
streamChecker.query('g').
         // return false
streamChecker.query('h').
         // return false
streamChecker.query('i').
         // return false
streamChecker.query('j').
         // return false
streamChecker.query('k').
         // return false
streamChecker.query('l').
         // return true, because 'kl' is in the wordlist

 
Note:

1 <= words.length <= 2000
1 <= words[i].length <= 2000
Words will only consist of lowercase English letters.
Queries will only consist of lowercase English letters.
The number of queries is at most 40000.

I tried it in Python, but could not do it. Can you solve it?

Give me a the Python program you requested?
assistant
#Here is the Python program you requested.

from collections import defaultdict
class StreamChecker:

    def __init__(self, words):
        tr = lambda: defaultdict(tr)
        self.trie = tr()
        for w in words:
            cur_trie = self.trie[w[0]]
            for i in range(1, len(w)):
                cur_trie = cur_trie[w[i]]
            cur_trie['end'] = True
        self.tail = []

    def query(self, letter):
        self.tail = [node[letter] for node in self.tail + [self.trie] if letter in node]
        for node in self.tail:
            if 'end' in node:
                return True
        return False
        

# Your StreamChecker object will be instantiated and called as such:
# obj = StreamChecker(words)
# param_1 = obj.query(letter)