def plural(n, singular, plural=None, show_n=True):
    """Pluralize <singular> word by adding an s if n != 1.

    Arguments:
        n (int): number of things there are
        singular (str): singular form of word
        plural (str, optional): optional plural form, for when it's not just
            singular + 's'
        show_n (bool): whether to include n in the result string (default True)

    Returns:
        (str): "1 thing" if n == 1 or "n things" if n != 1
    """
    number = '%s ' % n if show_n else ''
    if n == 1:
        return "%s%s" % (number, singular)
    elif plural is not None:
        return "%s%s" % (number, plural)
    else:
        return "%s%ss" % (number, singular)