This script can be used to switch the pulseaudio sink of an application
to the next sink in the list of sinks. The sink is found by querying the
currently focused window from i3 and retrieving the PID via _NET_WM_PID
attribute using xprop. If that PID doesn't directly have sink attached,
the script searches for children of this PID having a sink and switches
those. This is useful to switch e.g. an mpv running inside a terminal.
