allow us to iterate over the output of our command

def next(self):
        """ allow us to iterate over the output of our command """

        if self._stopped_iteration:
            raise StopIteration()

        # we do this because if get blocks, we can't catch a KeyboardInterrupt
        # so the slight timeout allows for that.
        while True:
            try:
                chunk = self.process._pipe_queue.get(True, 0.001)
            except Empty:
                if self.call_args["iter_noblock"]:
                    return errno.EWOULDBLOCK
            else:
                if chunk is None:
                    self.wait()
                    self._stopped_iteration = True
                    raise StopIteration()
                try:
                    return chunk.decode(self.call_args["encoding"],
                        self.call_args["decode_errors"])
                except UnicodeDecodeError:
                    return chunk