For the purposes of dynamic patching, it would be very
useful if all canvases were uniquely addressable. For
[;pd-my_abstraction.pd foo bar(
Should retain its current behaviour and go to all
instances of that abstraction
[;pd-$0 foo bar(
Should go to its container canvas.
And the expanded $0 variable should work from other
canvases. E.g. if $0 above expands to 1001, then
[;pd-1001 foo bar(
should have the same effect as the above, but work from
any open canvas.