@Test public void testRmSingleElement() throws Exception {
        IntervalSet s = IntervalSet.of(1,10);
        s.add(-3,-3);
        s.remove(-3);
        String expecting = "{1..10}";
        String result = s.toString();
        assertEquals(expecting, result);
    }
The following was broken:
	    {'\u0000'..'s', 'u'..'\uFFFE'} & {'\u0000'..'q', 's'..'\uFFFE'}=
	    {'\u0000'..'q', 's'}!!!! broken...
	 	'q' is 113 ascii
	 	'u' is 117
tool-testsuite/test/org/antlr/v4/test/tool/TestIntervalSet.java