I have a function I am stubbing that gets called with multiple arguments. I want to check **just the first argument**. The rest are callback function, so I want to leave them alone. Thus, I might have the following 2 calls, using ajax as an example:

```
method.get = sinon.stub();
method.get(25,function(){/* success callback */},function(){/* error callback */});         
method.get(10,function(){/* success callback */},function(){/* error callback */});

```

I cannot use `method.get.calls...` because then it doesn't differentiate between the first one `get(25)` and the second `get(10)`. But if I use `method.get.withArgs(25).calls...` then it does not match either, because `withArgs()` matches **all** arguments, which this does not (and never could, with callbacks like that).

How do I get sinon stubs to check and set responses based on just the 1st arg?