public static boolean
equal(Object tree, Object other) {
if ( consp(tree) )
return ( consp(other) &&
equal(first((Cons) tree),
first((Cons) other)) &&
equal(rest((Cons) tree),
rest((Cons) other)) );
return eql(tree, other); }
public static boolean // leaf equality
eql(Object tree, Object other) {
return ( (tree == other) ||
( (tree != null) &&
(other != null) &&
tree.equals(other) ) ); }