shifby examination

shiftby was used to fix an inbound_decode bug. There was elsewhere where shiftby existed as an unused variable and was remove. Take a look if there might be something there. No known bug, and it may be unnecessary, just worth noting.

https://github.com/Sketch/tinyfugue/commit/ec8e69f155fb4fca34a4055c70609d6c2877cb61