anchor.diff:      (cd testing && ../build)
     '';
   
  -  installCheckPhase = "./run_tests";
  +  installCheckPhase = ''
  +    ./run_tests units
  +    ./run_tests binaries
  +
  +    # can also `./run_tests scripts`, but this fails due to lack of FSL package
  +    # (and there's no convenient way to disable individual tests)
  +  '';
     doInstallCheck = true;
   
     installPhase = ''
  
positive.code: 
    postInstall = ''
      for prog in $out/bin/*; do
        wrapProgram $prog --prefix PATH : ${lib.makeBinPath [ ants ]}
      done
    '';
  
  
negative.code:     python
      fftw
      libtiff
      libpng
      zlib
    ] ++ lib.optionals withGui [
      libGL
      libGLU
      libX11
  