In coroutining mode, if Number1 or Number2 are free variables, the call to (//)/3 is delayed until these variables are instantiated.
Success: //(11, 2, 5). //(11, -2, -5). Fail: //(1, 2, 3). Error: //(A, 2, 6). (Error 4). //(5, 2, r). (Error 5). //(6, 2.0, 3.0). (Error 5). //(2, 0, Result). (Error 20). //(4 + 2, 2, 12). (Error 24).