anchor.diff: -{ callPackage, wxGTK30, openssl_1_0_2 }:
  +{ callPackage, wxGTK30, openssl_1_0_2, autoconf269 }:
   
   rec {
     lib = callPackage ../development/beam-modules/lib.nix {};
  
positive.code:     # R20
      erlangR20 = lib.callErlang ../development/interpreters/erlang/R20.nix {
        wxGTK = wxGTK30;
      };
      erlangR20_odbc = erlangR20.override { odbcSupport = true; };
      erlangR20_javac = erlangR20.override { javacSupport = true; };
  
negative.code:     erlangR19 = lib.callErlang ../development/interpreters/erlang/R19.nix {
        wxGTK = wxGTK30;
        openssl = openssl_1_0_2;
        autoconf = autoconf269;
      };
      erlangR19_odbc = erlangR19.override { odbcSupport = true; };
      erlangR19_javac = erlangR19.override { javacSupport = true; };
  