'Returns a short string representing the permission bits.  Looks like
what is printed by command line utilities such as \'ls -l\'
(e.g. \'rwx-wx--x\')
@return: The shorthand string.
@rtype: L{str}'

def shorthand(self):

    return ''.join([x.shorthand() for x in (self.user, self.group, self.other)])
