[luatex] object returned by lang.new

[Daniel Flipo]

Hi all,

Sorry for this stupid question, but I can't figure out how to get the 
name of <language> object returned by lang.new() when called during the 
luatex/lualatex format building :-(

I need it to compute the <number> id for French with lang.id() in order 
to compare it to glyph_nodes '.lang' id and decide whether the current 
language is French or not.

Thanks in advance for your hints and best wishes,
--
Daniel Flipo