如何从JSON对象的key生成所有组合？

def generate_combinations(json_obj):
    combinations = []
    keys = list(json_obj.keys())
    n = len(keys)

    def backtrack(index, curr_combination):
        if index == n:
            combinations.append(curr_combination)
            return

        key = keys[index]
        values = json_obj[key]
        for value in values:
            new_combination = curr_combination.copy()
            new_combination[key] = value
            backtrack(index + 1, new_combination)

    backtrack(0, {})
    return combinations

json_obj = {
    "color": ["red", "blue"],
    "size": ["small", "large"],
    "shape": ["circle", "square"]
}

combinations = generate_combinations(json_obj)
for combination in combinations:
    print(combination)

{'color': 'red', 'size': 'small', 'shape': 'circle'}
{'color': 'red', 'size': 'small', 'shape': 'square'}
{'color': 'red', 'size': 'large', 'shape': 'circle'}
{'color': 'red', 'size': 'large', 'shape': 'square'}
{'color': 'blue', 'size': 'small', 'shape': 'circle'}
{'color': 'blue', 'size': 'small', 'shape': 'square'}
{'color': 'blue', 'size': 'large', 'shape': 'circle'}
{'color': 'blue', 'size': 'large', 'shape': 'square'}