[CMake] how to write a cmake function with 2 or 3 arguments?

[Arnaud GELAS]

Hi all,

I would like to write a cmake function with one optional 3rd argument, 
the two first are mandatory.
How to proceed?

Let's take the following example:

function( add_sikuli_test arg1 arg2 arg3 )
     ...
endfunction( add_sikuli_test )


Thanks,
Arnaud