title: return tuple from a method
body: <p>I am writing a method which returns a tuple on success but <code>None</code> on failure. I have not yet finalized on <code>None</code> (as a failure case return) but it is one of the choices. Can we return <code>-1,-1</code> for failure case? I am looking for best pythonic way to achieve this so that unpacking is easy.</p>
  
  <p>Please let me know how we can improve it. Pseudo code is given below</p>
  
  <pre><code> def myFunc(self):
       if self.validate() != 0:
           return
       x,y = self.getXY()
  
       return x,y
  </code></pre>