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

def shorthand(self):

    returnval = ['r', 'w', 'x']
    i = 0
    for val in (self.read, self.write, self.execute):
        if (not val):
            returnval[i] = '-'
        i += 1
    return ''.join(returnval)
