human
Here's a good function header given the following:
I wrote the below code

    minutes_left = (seconds_left // 60)
    seconds_left %= 60
    hours_left = (minutes_left // 60)
    minutes_left %= 60
    days_left = (hours_left // 24)
    hours_left %= 24
    def helper(cnt, name):
        return '{}    {}{}'.format(str(cnt), name, ('s' if (cnt > 1) else ''))
    if (days_left > 0):
        msg = helper(days_left, 'day')
        if (hours_left > 0):
            msg += ('    and    ' + helper(hours_left, 'hour'))
        return msg
    if (hours_left > 0):
        msg = helper(hours_left, 'hour')
        if (minutes_left > 0):
            msg += ('    and    ' + helper(minutes_left, 'minute'))
        return msg
    if (minutes_left > 0):
        return helper(minutes_left, 'minute')
    return 'less    than    a    minute'

What's a good function header?
assistant
#Here's a good function header.

def pretty_eta(seconds_left):