title: When using Sinon, how to replace stub function in a stub instance?
body: <p>If I have create a instance by  <code>var a = sinon.createStubInstance(MyContructor)</code>.</p>
  
  <p>How can I replace one of the stubbed function like <code>var stub = sinon.stub(object, "method", func);</code>.</p>
  
  <p>The main reason I am doing this is want to achieve multiple callback workaround as <a href="https://stackoverflow.com/questions/29818811/sinon-js-stub-can-you-call-more-than-one-callback-on-a-single-stubbed-function">this mentioned</a></p>