boolean callbackWithClass1Param(
    in Class1 class1Param); 

boolean callbackWithClass2Param(
    in Class2 class2Param,
    in DOMString strArg); 

long callbackWithNonBoolReturnType(
    in Class3 class3Param); 

long customCallback(
    in Class5 class5Param,
    in Class6 class6Param);