def test_rstrip(self, size):
        SUBSTR = ' abc def ghi'
        s = SUBSTR.ljust(size)
        self.assertEquals(len(s), size)
        self.assertEquals(s.rstrip(), SUBSTR.rstrip())
        del s
        s = SUBSTR.rjust(size)
        self.assertEquals(len(s), size)
        stripped = s.rstrip()
        self.failUnless(stripped is s)