def get_sleepiest_minute(guard_sleep):
    """For a guard's sleep record, return the minute he was most often asleep.

    returns: (most_slept_minute, times_slept_that_minute)
    """
    sleepiest = 0, 0
    for minute in guard_sleep:
        if guard_sleep[minute] > sleepiest[1]:
            sleepiest = minute, guard_sleep[minute]
    return sleepiest