@staticmethod
def pluralize(realised):
    """Return the plural form of the argument realisation string."""
    if realised.endswith((u's', u'x', u'z')):
        return realised
    elif realised.endswith((u'au', u'eu')):
        return '%sx' % realised
    elif realised.endswith(u'al'):
        return '%saux' % realised[:-2]
    else:
        return '%ss' % realised
