anchor.diff:  
       src = fetchurl {
         url = "https://releases.mattermost.com/${version}/mattermost-${version}-linux-amd64.tar.gz";
  -      sha256 = "1bm5nqnhk2w3sy8mvm81k7d65j6bgpvakgphgwqgnlm864i4253z";
  +      sha256 = "1yzhy37frbhik6iq5z8bglpfcjlwnbgcf5iy1davkh7iqpcbxb0s";
       };
   
       installPhase = ''
  
positive.code: { stdenv, fetchurl, fetchFromGitHub, buildGoPackage, buildEnv }:
  
  let
    version = "5.1.0";
  
    mattermost-server = buildGoPackage rec {
      name = "mattermost-server-${version}";
  
negative.code:       owner = "mattermost";
        repo = "mattermost-server";
        rev = "v${version}";
        sha256 = "0hll62ad12drlqarr7y7zvjj0b12snqm8j5k923lj0064nlpc47z";
      };
  
      goPackagePath = "github.com/mattermost/mattermost-server";
  