static void compareFunction(String functionName, String expected, String input) {
Parser parser = new LexprParser(new Tokenizer(input).tokenize());
Unit unit = parser.script(null);
Assert.assertNotNull("Parser returned no output", unit);
FunctionDecl function = unit.resolveFunction(functionName, false);
Assert.assertNotNull("No such function " + functionName, function);
String stringified = LexprParser.stringify(function);