def min_oslevel(dic):
    """
    Find the minimun value of a dictionnary.

    arguments:
        dict - Dictionnary {machine: oslevel}
    return:
        minimun oslevel from the dictionnary
    """
    oslevel_min = None

    for key, value in iter(dic.items()):
        if oslevel_min is None or value < oslevel_min:
            oslevel_min = value

    return oslevel_min