Update project.v

src/project.v

@@ -18,7 +18,7 @@ module tt_um_example (
 
   // All output pins must be assigned. If not used, assign to 0.
   assign uo_out  = ui_in + uio_in;  // Example: ou_out is the sum of ui_in and uio_in
-  assign uio_out = 0;
+  assign uio_out = ui_in - uio_in;
   assign uio_oe  = 0;
 
   // List all unused inputs to prevent warnings