else if ("output".equals(tree.head())) return string(tree.children());
else if ("input".equals(tree.head())) return string(tree.children());
else if ("testcase".equals(tree.head())) {
String input = string(tree.child(0));
String[] output = tree.numChildren()>2 ? ((String[])walk(tree, 1)) : new String[0];
else if ("output".equals(tree.head())) return string(tree.children());
else if ("input".equals(tree.head())) return string(tree.children());
else if ("testcase".equals(tree.head())) {
String input = string(tree.child(0));
String[] output = tree.numChildren()>2 ? ((String[])walk(tree, 1)) : new String[0];