class CombinatoricalUtils:
    # combo related algorithmic tools
    def __init__(self):
        self.result: list[str] = []

    def _generatePermutations(self, lists: list[list[str]], result: list[str], depth: int, current: str):
        # this function has a private modifier (the "_" makes it so)
        if depth == len(lists):
        for i in range(0, len(lists) + 1):
            self._generatePermutations(lists, result, depth + 1, current + lists[depth][i])

    def generatePermutations(self, lists: list[list[str]]):
        # generate all permutations between all string lists in lists, which is a list of lists of strings
        self.result = []
        self._generatePermutations(lists, self.result, 0, "")

    def generatePermutations(self, *lists: list[list[str]]):
        # this is the varargs vertion of this function
        # example method call: cu.generatePermutations(l1,l2)
        temp_lists:list[list[str]] = []
        for i in range(0, len(lists)):
        self.result = []
        self._generatePermutations(temp_lists, self.result, 0, "")