如何打印嵌套字典[Python]中特定键的值的总和？

def print_nested_dict_sum(nested_dict, target_key, total_sum=0):
    for key, value in nested_dict.items():
        if key == target_key:
            total_sum += value
        elif isinstance(value, dict):
            total_sum = print_nested_dict_sum(value, target_key, total_sum)
    return total_sum

# 示例嵌套字典
nested_dict = {
    'a': 1,
    'b': {
        'c': 2,
        'd': {
            'e': 3,
            'f': 4
        }
    },
    'g': 5
}

# 打印键'd'的值的总和
target_key = 'd'
result = print_nested_dict_sum(nested_dict, target_key)
print(f"The sum of values for key '{target_key}' is: {result}")

The sum of values for key 'd' is: 7