IsRebar3 = erlang:function_exported(rebar3, main, 1),
case IsRebar3 of
  true ->
    CONFIG;
  false ->
    URLs = [ {snappyer, "https://github.com/zmstone/snappyer"}
           , {crc32cer, "https://github.com/zmstone/crc32cer"}
           ],
    Rebar3Deps = proplists:get_value(deps, CONFIG),
    Rebar2Deps =
      lists:map(
        fun({Name, URL}) ->
          Tag = proplists:get_value(Name, Rebar3Deps),
          {Name, ".*", {git, URL, {tag, Tag}}}
        end, URLs),
    lists:keyreplace(deps, 1, CONFIG, {deps, Rebar2Deps})
end.