anchor.diff:  
   let
     inherit (lib)
  -    replaceStrings;
  +    optionalString
  +    replaceStrings
  +    versionAtLeast;
   
     sources = {
       "5.2" = {
  
positive.code:       sha256 = "b9e2e4aad6789b3b63a056d442f7b39f0ecfca3ae0f1fc0ae4e9614401b69f4b";
      };
      "5.3" = {
        version = "5.3.4";
        multihash = "QmNYqRyfDBStum87ptEAZWBbjAXKC6pmZX9vuJzcdhK5Ru";
        sha256 = "f681aa518233bc407e23acf0f5887c884f17436f000d453b2491a9f11a52400c";
      };
    };
    source = sources."${channel}";
  
negative.code:     })
    ];
  
    postPatch = optionalString (versionAtLeast source.version "5.3.4") ''
      grep -q '$V\.4' Makefile
      sed -i "s,\$V\.4,${source.version}," Makefile
    '' + ''
      grep -q '/usr' src/luaconf.h
      sed -i "/LUA_ROOT/ s,/usr,$out," src/luaconf.h
    '';
  
  