<a href="#val-read_joined"><code>read_joined</code></a> but reads stdout and stderr as a separate strings streams, returning a pair of strings wrapped in the ouput type. This function uses asynchronous I/O internally, so the optional <code>sleep</code> parameter is provided as a means to pause briefly if output is expected to be slow to avoid pegging the CPU with a loop that does nothing.</p></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-lines_both"><a href="#val-lines_both" cla