anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "pg_topn";
  -  version = "2.3.0";
  +  version = "2.3.1";
   
     buildInputs = [ postgresql ];
   
  
positive.code:   meta = with stdenv.lib; {
      description = "Efficient querying of 'top values' for PostgreSQL";
      homepage    = "https://github.com/citusdata/postgresql-topn";
      maintainers = with maintainers; [ thoughtpolice ];
      platforms   = postgresql.meta.platforms;
      license     = licenses.agpl3;
  
negative.code:     owner  = "citusdata";
      repo   = "postgresql-topn";
      rev    = "refs/tags/v${version}";
      sha256 = "0ai07an90ywhk10q52hajgb33va5q76j7h8vj1r0rvq6dyii0wal";
    };
  
    installPhase = ''
  