[NTG-context] Evaluating a lua expression at the end (again)

Dear ConTeXt users, Last time, this is what I wanted, and Hans provided me an example: https://www.mail-archive.com/ntg-context@ntg.nl/msg78079.html However, the example given in that e-mail does not work with my Debian context 2016.05.17.20160523-1. Could you please help me out again? I get: /usr/share/texmf/tex/context/base/mkiv/core-uti.lua:165: attempt to index upvalue 'tobesavedmacros' (a nil value) Thanks. Kumar -- Kumar Appaiah