anchor.diff:  
     smartcrop = buildFromGitHub {
       version = 5;
  -    rev = "c2a0373a193bac1daf8b6691e2ece069c5d7ac7f";
  +    rev = "f6ebaa786a12a0fdb2d7c6dee72808e68c296464";
       owner  = "muesli";
       repo   = "smartcrop";
  -    sha256 = "1430gl8ym2vpjzmma0rrf6pdz2jvjxliij2qpq598jlwaq5g4x38";
  -    date = "2018-02-21";
  +    sha256 = "1fcbivf87z5kx9y87xmgmnfqp3llnrpm1jv5ci5g1czz9dggzh4b";
  +    date = "2018-02-28";
       propagatedBuildInputs = [
         image
         resize
  
positive.code: 
    geoip2-golang = buildFromGitHub {
      version = 5;
      rev = "v1.2.0";
      owner = "oschwald";
      repo = "geoip2-golang";
      sha256 = "1f8nwg0m2lfr9y2509drwqkrrqdwnd1v9pf9kyg0vq2g2wb18w6n";
      propagatedBuildInputs = [
        maxminddb-golang
      ];
  
negative.code: 
    dnscrypt-proxy = buildFromGitHub {
      version = 5;
      rev = "2.0.6";
      owner  = "jedisct1";
      repo   = "dnscrypt-proxy";
      sha256 = "1i04rsk7d4am755qspqn7bk1xcadssyq54sygrl0dlxs89qycc7n";
      propagatedBuildInputs = [
        cachecontrol
        crypto
  