anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "fmt";
  -  version = "6.2.0";
  +  version = "6.2.1";
   
     outputs = [ "out" "dev" ];
   
  
positive.code:     owner = "fmtlib";
      repo = "fmt";
      rev = version;
      sha256 = "1vr08a8q94j66gas7ddbpdbq72b2ikd0mkgd5zd3l63610n8qajs";
    };
  
    patches = [
  
negative.code:     (fetchpatch {
        url = "https://github.com/fmtlib/fmt/commit/78f041ab5b40a1145ba686aeb8013e8788b08cd2.patch";
        sha256 = "hjE6Q/ubA4UhvuJXgcsA3wiGoDK031P19njQRL9JF8M=";
      })
  
      # Fix cmake config paths.
      (fetchpatch {
        url = "https://github.com/fmtlib/fmt/pull/1702.patch";
        sha256 = "18cadqi7nac37ymaz3ykxjqs46rvki396g6qkqwp4k00cmic23y3";
      })
    ];
  
  