    @Test
    public void validProperties() {

        assertEquals(4, lex("a~i~").size());
        assertEquals(4, lex("~i~b").size());
        assertEquals(6, lex("~i~~id~").size());
        assertEquals(7, lex("~i~ ~id~").size());
        assertEquals(7, lex("~i~\n~id~").size());
        assertEquals(7, lex("~i~\t~id~").size());
        assertEquals(7, lex("~i~\t~id~\n").size());
    }