def infer_time_unit(time_seconds_arr):
    """
    Determine the most appropriate time unit for an array of time durations
    specified in seconds.
    e.g. 5400 seconds => 'minutes', 36000 seconds => 'hours'
    """
    if len(time_seconds_arr) == 0:
        return 'hours'
    max_time_seconds = max(time_seconds_arr)
    if max_time_seconds <= 60 * 2:
        return 'seconds'
    elif max_time_seconds <= 60 * 60 * 2:
        return 'minutes'
    elif max_time_seconds <= 24 * 60 * 60 * 2:
        return 'hours'
    else:
        return 'days'
Determine the most appropriate time unit for an array of time durations
    specified in seconds.
    e.g. 5400 seconds => 'minutes', 36000 seconds => 'hours'