/usr/lib/erlang/lib/runtime_tools-1.9.3/ is in erlang-src 1:18.3-dfsg-1ubuntu3.
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/usr/lib/erlang/lib/runtime_tools-1.9.3/src/
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/appmon_info.erl
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/dbg.erl
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/dyntrace.erl
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/erts_alloc_config.erl
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/observer_backend.erl
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/percept_profile.erl
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/runtime_tools.erl
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/runtime_tools_sup.erl
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/system_information.erl
/usr/lib/erlang/lib/runtime_tools-1.9.3/src/ttb_autostart.erl