prettify symbols question

[Alfred M. Szmidt]

Not sure if this is better for help-gnu-emacs or here.

What would the proper way to handle say #o210 in prettify-symbols?

I've attached a simple test, I would expect to see the #o210 sequence
in the file to be shown as a unicode lambda, but nothing changes -- I
suspect it is due to some encoding mismatch between the buffer and the
string.

prettify-test.el
Description: application/emacs-lisp