How to test if a personnal class (or module) exist ???

I have developped a specific class for my watchface, only for OLED models. As this use some memory, I have set the folowing lines in my Monkey.jungle :

d2air.sourcePath = source;source_Oled
d2airx10.sourcePath = source;source_Oled
d2mach1.sourcePath = source;source_Oled
epix2.sourcePath = source;source_Oled
fenix7.sourcePath = source
etc etc ...
My Oled class is in source_oled folder
In my other class, I want to test if I can execute code in DessinEcranOled Class, but I don't know how to do this. I have tried many things like 
//try with Application
if (Application has :DessinEcranOled) {
	//run Oled functions in class DessineEcranOled
}

//try with App
if (App has :DessinEcranOled) {
	//run Oled functions in class DessineEcranOled
}

//try with App.Appbase
if (App.AppBase has :DessinEcranOled) {
	//run Oled functions in class DessineEcranOled
}

//try with Self
if (Self has :DessinEcranOled) {
	//run Oled functions in class DessineEcranOled
}
But It doesn't work
I would like to use the same code for Fenix 7 and Epix2, but with more for Epix2, and I don't know how to do this
Your help would be welcome, Thanks