title: in python i want to return none instead of empty string
body: <p>i want to return none but that gives me an error 
  i do not want to return empty strings </p>
  
  <pre><code>def read_line2(self, timeout=None):  ## Read Radio2 Serial line
          try:
              return self._rq2.get(block=timeout, timeout=timeout)
          except Empty:
              return ''
  </code></pre>