def large_num_formatter(num, pos=None):
    """
    Format large numbers using appropriate sufixes for powers of 1000

    Parameters:
        num: (int): The tick value to be formatted
        pos: (int): Position of the ticker
    """
    for unit in ['', 'mil', 'Mi.', 'Bi.']:
        if abs(num) < 1000.0:
            return "%3.1f %s" % (num, unit)
        num /= 1000.0
    return "%.1f %s" % (num, 'Tri.')