anchor.diff:      optionals
       optionalString
       platforms;
  -in
  -
  -let
  +
     optionalPlugins = {
       # TODO: write a generic function to detect null dependencies
       acousticbrainz =
  
positive.code:       test/test_replaygain.py
    '';
  
    preFixup = ''
      wrapProgram $out/bin/beet \
        --prefix 'GI_TYPELIB_PATH' : "$GI_TYPELIB_PATH" \
  
negative.code:       }
      );
  
    patches = [
      (fetchTritonPatch {
        rev = "d3fc5e59bd2b4b465c2652aae5e7428b24eb5669";
  