def flatten(iterable, n=1):
    """
    remove n levels of list nesting for a list of lists
    assumes uniform nesting
    :param iterable: nested list of lists to be flattened
    :param n: how many levels of nesting to remove
    :return: flattened list
    """
    tmp = iterable
    for _ in range(n):
        tmp = [item for sublist in tmp for item in sublist]
    return tmp