I want to practise writing apex class, please can anyone provide a link where i can get different scenarios for writing apex classes

Hi,

I have a process builder workflow setup that sends out new task email notifications.  I would like to differentiate the the email notifications based on the queue that it is getting sent to.  

A simplified example is that we have one queue that is for the US Sales and another queue that is for International Sales.  I would like one style email template to be sent for the US and another for international.  I don't want to go off of the queue name since I would need to maintain that and this list will grow over time.

I originally was looking into custom metadata types, but not sure if that will work.  Any advise is greatly appreciated!  Thanks!