call to test_loop ([[a, b], [a, b]])
    in the loop the param should not be changed : ([[a, b], [a, b]])
call to test_loop ([a, b])
    in the loop the param should not be changed : ([a, b])
call to test_loop (a)
return
    in the loop the param should not be changed : ([a, b])
call to test_loop (b)
return
return
    in the loop the param should not be changed : ([[a, b], [a, b]])
call to test_loop ([a, b])
    in the loop the param should not be changed : ([a, b])
call to test_loop (a)
return
    in the loop the param should not be changed : ([a, b])
call to test_loop (b)
return
return
return