'Given a short verbnet class identifier (eg \'37.10\'), map it
to a long id (eg \'confess-37.10\').  If ``shortid`` is already a
long id, then return it as-is'

def longid(self, shortid):

    if self._LONGID_RE.match(shortid):
        return shortid
    elif (not self._SHORTID_RE.match(shortid)):
        raise ValueError((u'vnclass    identifier    %r    not    found' % shortid))
    try:
        return self._shortid_to_longid[shortid]
    except KeyError:
        raise ValueError((u'vnclass    identifier    %r    not    found' % shortid))
