def next_message (self): # pragma: no cover

        try:
            return self._queue.get(False)

        except Queue.Empty:
            return None
redraw the graphic PSD plot if needed i.e.new data have been given to get_psd
dataset/ETHPy150Open rapidsms/rapidsms-core-dev/lib/rapidsms/backends/base.py/BackendBase.next_message--crossover with--dataset/ETHPy150Open ericgibert/supersid/supersid/tksidviewer.py/tkSidViewer.refresh_psd