anchor.diff:      "--enable-man"
       "--${boolEn (gobject-introspection != null)}-introspection"
       "--${boolWt (libjpeg != null)}-libjpeg"
  -    "--${boolWt (libtiff != null)}-libtiff"
  +    "--${boolWt (libtiff != null && zlib != null)}-libtiff"
       "--${boolWt (lcms2 != null)}-liblcms2"
     ];
   
  
positive.code: , libjpeg
  , libpng
  , libtiff
  
  , channel
  }:
  
negative.code:     libjpeg
      libpng
      libtiff
      zlib
    ];
  
    configureFlags = [
  