[luatex] token.expand: how to use it?

[Eduardo Ochs]

Hi list,

how do I use the function token.expand, that is (very) briefly
mentioned here?

  http://mirrors.ibiblio.org/CTAN/systems/doc/luatex/luatex.pdf#page=224

I've put this in a .tex file

  \def\foo{FOO}
  \def\bletch#1{BL#1ETCH}

and entered a Lua REPL. All the "print"s below give meaningful
results,

  print(token.get_macro("foo"))
  print(token.get_macro("bletch"))
  print(token.get_meaning("foo"))
  print(token.get_meaning("bletch"))
  print(token.create("bletch"))
  print(token.create("bletch").expandable)

and the last one says "true"... but I've tried to call token.expand
with several kinds of arguments, and in all cases I got this error,

  ! Undefined control sequence.
  \repl ->\directlua { print(); run_repl2_now() }

where \repl is the tex macro that I use to run my Lua REPL...

Help please, and thanks in advance... =/
  Eduardo Ochs
  http://angg.twu.net/dednat6.html