array nums of unique integers, return all possible combination of subsets of nums.

subset_combination.py

class Solution:
    def subsets(self, nums: List[int]) -> List[List[int]]:
        def do_generate(result, slate, subset):
            result += [slate]
            for idx, num in enumerate(subset):
                new_subset = subset[idx+1:]
                do_generate(result, slate + [num], new_subset)
            return result
        return do_generate([], [], nums)