制作一种特殊类型的字典

class HashTable:
    def __init__(self, size):
        self.size = size
        self.table = [[] for _ in range(size)]

    def hash_function(self, key):
        return hash(key) % self.size

    def insert(self, key, value):
        index = self.hash_function(key)
        for item in self.table[index]:
            if item[0] == key:
                item[1] = value
                return
        self.table[index].append([key, value])

    def get(self, key):
        index = self.hash_function(key)
        for item in self.table[index]:
            if item[0] == key:
                return item[1]
        raise KeyError(key)

import threading

class ConcurrentHashTable:
    def __init__(self):
        self.table = {}
        self.lock = threading.Lock()

    def insert(self, key, value):
        with self.lock:
            self.table[key] = value

    def get(self, key):
        with self.lock:
            return self.table.get(key)