import itertools


def remove_duplicates(llist):
    """
    Removes any and all duplicate entries in the specified list.

    This function is intended to be used during dataset merging and
    therefore must be able to handle list-of-lists.

    :param llist: The list to prune.
    :return: A list of unique elements only.
    """
    if not llist:
        return []

    llist.sort()

    return [x for x, _ in itertools.groupby(llist)]