echo foo # Can be captured
    echo foo >&2 # Can be captured
    echo foo >&3 # Cannot be captured (with open3)

##</code><code>##

    # Currently mixes output due to fd 3 not buffered
    parallel 'echo {} start >&3;sleep 10;echo {} end >&3' ::: a b c 3>out.file

##</code><code>##

    # This currently works
    parallel 'echo {} start >&2;sleep 10;echo {} end >&2' ::: a b c 2>out.file