ensure(arity); // Ensure presence of superclass.
String super_type = EFUN_TYPE.getInternalName() + arity;
String self_type = super_type + "Guard";
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES|ClassWriter.COMPUTE_MAXS);
cw.visit(Opcodes.V1_5, Opcodes.ACC_PUBLIC | Opcodes.ACC_ABSTRACT,
self_type, null, super_type, null);
// TODO: Factor out default-constructor creation.
MethodVisitor mv = cw.visitMethod(Opcodes.ACC_PUBLIC/*PROTECTED*/, "<init>", "()V", null, null);
mv.visitCode();