from typing import Iterable
from typing import List


def arg_sort(unsorted_iterable: Iterable) -> List[int]:
    """Argument-sort an iterable.

    :param unsorted_iterable: An iterable of unsorted items.
    :return: A list of sorted items' indices.
    """
    return [i[0] for i in sorted(enumerate(unsorted_iterable), key=lambda x: x[1])]