获取列表python的所有加减组合

def get_combinations(nums):
    if len(nums) == 1:
        return [nums]
    else:
        result = []
        for i in range(len(nums)):
            rest = nums[:i] + nums[i+1:]
            for combination in get_combinations(rest):
                result.append([nums[i]] + combination)
                result.append([-nums[i]] + combination)
        return result

nums = [1, 2, 3]
combinations = get_combinations(nums)
print(combinations)

[[1, 2, 3], [1, 2, -3], [1, -2, 3], [1, -2, -3], [-1, 2, 3], [-1, 2, -3], [-1, -2, 3], [-1, -2, -3]]