public MethodMemberNode firstMethod() {
   for (AbstractNode n : this) {
     if (n instanceof ReferenceNode) {
       if (n.insn() instanceof MethodInsnNode) return (MethodMemberNode) n;
     }
   }
   return null;
 }
 public FieldMemberNode firstField() {
   for (AbstractNode n : this) {
     if (n instanceof ReferenceNode) {
       if (n.insn() instanceof FieldInsnNode) return (FieldMemberNode) n;
     }
   }
   return null;
 }