TestCase tc = new TestCase(input, output, grammar, false, false);
return tc;
} else if ("ts".equals(tree.head())) return walk(tree, 0);
else if (tree.head() == null) {
TestCase tc = new TestCase(input, output, grammar, false, false);
return tc;
} else if ("ts".equals(tree.head())) return walk(tree, 0);
else if (tree.head() == null) {