如何获取键之前和键后的值

# 示例字典
data = {
    'key1': 'value1',
    'key2': 'value2',
    'key3': 'value3',
    'key4': 'value4'
}

def get_previous_and_next_value(dictionary, key):
    keys = list(dictionary.keys())
    index = keys.index(key)
    
    previous_key = keys[index-1] if index > 0 else None
    next_key = keys[index+1] if index < len(keys)-1 else None
    
    previous_value = dictionary[previous_key] if previous_key else None
    next_value = dictionary[next_key] if next_key else None
    
    return previous_value, next_value

# 示例用法
key = 'key3'
previous_value, next_value = get_previous_and_next_value(data, key)

print(f"键'{key}'之前的值为: {previous_value}")
print(f"键'{key}'之后的值为: {next_value}")

键'key3'之前的值为: value2
键'key3'之后的值为: value4