title: Python Mock - return_value - getting the "real" return value
body: <p>When using <code>patch.object</code> in order to mock a method, is there a way to specify that for certain parameters values, the method will run as it was not mocked at all, and will return the "real" return_value, and for other parameters values to set a specific return_value?</p>
  
  <p>Thanks.</p>