def flatten(l: list) -> list:
    """
    1.2
    Flatten a multi dimensional list
    [[1, 2], [2, 4]], gives : [1, 2, 2, 4]
    """
    flat_list = []

    for el in l:
        if isinstance(el, list):
            flat_list.extend(flatten(el))
        else:
            flat_list.append(el)

    return flat_list