anchor.diff:  
       for cmd in $out/bin/* ; do
         wrapProgram "$cmd" \
  -        --set TCLLIBPATH "${tcl}/${tcl.libdir}" \
           --set TK_LIBRARY "${tk}/lib/${tk.libPrefix}"
       done
     '';
  
positive.code:     platforms = lib.platforms.linux;
    };
  }
  
  
negative.code: { lib, fetchurl, tcl, tk, libX11, zlib, makeWrapper, makeDesktopItem }:
  
  tcl.mkTclDerivation rec {
    pname = "scid-vs-pc";
    version = "4.21";
  
  