callback.append(fact.ALOAD_0);
callback.append(InstructionConstants.ALOAD_0);
    InstructionList makeCallToCallback(LazyMethodGen callbackMethod) {    	InstructionFactory fact = getFactory();        InstructionList callback = new InstructionList();        if (thisVar != null) {        	callback.append(fact.ALOAD_0);         }        if (targetVar != null && targetVar != thisVar) {            callback.append(BcelRenderer.renderExpr(fact, world, targetVar));        }        callback.append(BcelRenderer.renderExprs(fact, world, argVars));        // remember to render tjps        if (thisJoinPointVar != null) {        	callback.append(BcelRenderer.renderExpr(fact, world, thisJoinPointVar));        }        callback.append(Utility.createInvoke(fact, callbackMethod));        return callback;    }