如何在哈希数组中映射get操作？

class HashMap:
    def __init__(self):
        self.size = 1000
        self.map = [None] * self.size

    def _get_hash(self, key):
        hash = 0
        for char in str(key):
            hash += ord(char)
        return hash % self.size

    def add(self, key, value):
        key_hash = self._get_hash(key)
        key_value = [key, value]

        if self.map[key_hash] is None:
            self.map[key_hash] = list([key_value])
            return True
        else:
            for pair in self.map[key_hash]:
                if pair[0] == key:
                    pair[1] = value
                    return True
            self.map[key_hash].append(key_value)
            return True

    def get(self, key):
        key_hash = self._get_hash(key)
        if self.map[key_hash] is not None:
            for pair in self.map[key_hash]:
                if pair[0] == key:
                    return pair[1]
        return None

# 创建哈希数组对象
hash_map = HashMap()

# 向哈希数组中添加键值对
hash_map.add("name", "John")
hash_map.add("age", 25)
hash_map.add("city", "New York")

# 获取键对应的值
name = hash_map.get("name")
age = hash_map.get("age")
city = hash_map.get("city")

print(name)  # 输出：John
print(age)  # 输出：25
print(city)  # 输出：New York