anchor.diff: -{stdenv, fetchurl, makeWrapper, ncurses, perl, fortune}:
  +{stdenv, fetchurl, makeWrapper, libiconv, ncurses, perl, fortune}:
   
   stdenv.mkDerivation rec {
     name = "gtypist-${version}";
  
positive.code:     homepage = http://www.gnu.org/software/gtypist;
      description = "Universal typing tutor";
      license = licenses.gpl3Plus;
      platforms = platforms.linux;
      maintainers = with maintainers; [ pSub ];
    };
  }
  
negative.code:     sha256 = "0xzrkkmj0b1dw3yr0m9hml2y634cc4h61im6zwcq57s7285z8fn1";
    };
  
    buildInputs = [ makeWrapper ncurses perl fortune ]
     ++ stdenv.lib.optional stdenv.isDarwin libiconv;
  
    preFixup = ''
       wrapProgram "$out/bin/typefortune" \
  