def format_interval(seconds):
    """ Format an integer number of seconds to a human readable string."""
    units = [
        (('week', 'weeks'), 604800),
        (('day', 'days'), 86400),
        (('hour', 'hours'), 3600),
        (('minute', 'minutes'), 60),
        #(('second', 'seconds'), 1)
    ]
    result = []
    for names, value in units:
        n, seconds = divmod(seconds, value)
        if n > 0:
            result.append('%d %s' % (n, names[n > 1]))
    if seconds:
        result.append("%.2f %s" % (seconds, ['second', 'seconds'][seconds != 1.0]))
    return ', '.join(result)