问在函数内移动迭代工具产品时，"TypeError：'int‘对象不可迭代“

EN

TypeError: 'int' object is not iterable

#!/usr/bin/env python

import itertools

def main():

    elements_specification = [[10, 20], [30, 40], [50, 60]]

    lists = [list(list_generated) for index, element_specification in enumerate(elements_specification) for list_generated in itertools.product(*elements_specification[:index + 1])]

    for list_configuration in lists:
        print(list_configuration)

    print("---")

    for list_configuration in list_element_combinations_variadic(
        [[10, 20], [30, 40], [50, 60]]
    ):
        print(list_configuration)

def list_element_combinations_variadic(
    elements_specification
    ):
    """
    This function accepts a specification of lists of elements for each place in
    lists in the form of a list, the elements of which are lists of possible
    elements and returns a list of lists corresponding to the combinations of
    elements of the specification with varying numbers of elements.

    For example, the list elements specification [[10, 20], [30, 40], [50, 60]]
    yields the following lists:

    [10]
    [20]
    [10, 30]
    [10, 40]
    [20, 30]
    [20, 40]
    [10, 30, 50]
    [10, 30, 60]
    [10, 40, 50]
    [10, 40, 60]
    [20, 30, 50]
    [20, 30, 60]
    [20, 40, 50]
    [20, 40, 60]
    """
    lists = [list(list_generated) for index, elements_specification in enumerate(elements_specification) for list_generated in itertools.product(*elements_specification[:index + 1])]
    return lists

if __name__ == "__main__":
    main()