/usr/lib/erlang/lib/tools-2.9/emacs/ is in erlang-tools 1:19.2.1+dfsg-2+deb9u2.
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/usr/lib/erlang/lib/tools-2.9/emacs/README
/usr/lib/erlang/lib/tools-2.9/emacs/erlang-edoc.el
/usr/lib/erlang/lib/tools-2.9/emacs/erlang-eunit.el
/usr/lib/erlang/lib/tools-2.9/emacs/erlang-flymake.el
/usr/lib/erlang/lib/tools-2.9/emacs/erlang-skels-old.el
/usr/lib/erlang/lib/tools-2.9/emacs/erlang-skels.el
/usr/lib/erlang/lib/tools-2.9/emacs/erlang-start.el
/usr/lib/erlang/lib/tools-2.9/emacs/erlang.el
/usr/lib/erlang/lib/tools-2.9/emacs/erlang_appwiz.el
/usr/lib/erlang/lib/tools-2.9/emacs/erldoc.el
/usr/lib/erlang/lib/tools-2.9/emacs/test.erl.indented
/usr/lib/erlang/lib/tools-2.9/emacs/test.erl.orig