anchor.diff:      src
       nativeBuildInputs
       buildInputs
  -    cmakeFlags
       disallowedReferences
       stripDebugList
       doCheck
  
positive.code:   } // lib.optionalAttrs (hasFeature "gr-qtgui" features) {
      inherit (libsForQt5) qwt;
    };
  
    postInstall = shared.postInstall
      # This is the only python reference worth removing, if needed.
  
negative.code:       runtime = [ SDL ];
        cmakeEnableFlag = "GR_VIDEO_SDL";
      };
      gr-vocoder = {
        runtime = [ codec2 gsm ];
        cmakeEnableFlag = "GR_VOCODER";
      };
      gr-wavelet = {
        cmakeEnableFlag = "GR_WAVELET";
        runtime = [ gsl libsodium ];
  