assertEquals(lexSource.lookAheadElement(2).source, "ef");
lexSource.consumeInput();
lexSource.consumeInput();
assertEquals(lexSource.lookAheadElement(0).source, "ef");
assertTrue(lexSource.getSourcePosition() == 4);
lexSource.advanceSubChannelTokens();
assertTrue(lexSource.getSourcePosition() == 6);
assertEquals(lexSource.lookAheadElement(0).getStartPos(), 6);
assertEquals(lexSource.lookAheadElement(0).source, "ef");
}