def date_group(date):
    """date_group(date)
    
    Converts a date string into a year/season ID tuple.
    
    Positional arguments:
        date (str) - date string, in "MM/DD/YYYY" format
    
    Returns:
        (tuple) - tuple with 2-digit year and season ID
            (0 for Su, 1 for Fa, 2 for Sp)

    The cutoffs for Fall, Spring, and Summer are:
        Jan-May: Summer
        June-August: Fall
        September-December: (next) Spring
    """
    
    # Gather month, day, and year
    parts = date.split('/')
    if len(parts) != 3:
        raise ValueError('date string must be in "MM/DD/YYYY" format')
    m = int(parts[0])
    d = int(parts[1])
    y = int(parts[2])
    
    # Use month and day to determine season
    if m <= 5:
        return (y % 100, 0)
    elif m <= 8:
        return (y % 100, 1)
    else:
        return ((y + 1) % 100, 2)