anchor.diff:  
     # more is unavailable in darwin
     # just use less
  -  more_compat = runCommand "more" {} ''
  +  more_compat = runCommand "more-${version}" {} ''
       mkdir -p $out/bin
       ln -s ${pkgs.less}/bin/less $out/bin/more
     '';
  
positive.code:   };
  
    makeCompat = name': value: buildEnv {
      name = name' + "-compat";
      paths = value;
    };
  
  
negative.code: # input, not "procps" which requires Linux.
  
  let
    version = "1003.1-2008";
  
    singleBinary = cmd: providers: let
        provider = "${lib.getBin providers.${hostPlatform.parsed.kernel.name}}/bin/${cmd}";
      in runCommand "${cmd}-${version}" {
        meta.platforms = map (n: { kernel.name = n; }) (pkgs.lib.attrNames providers);
      } ''
        mkdir -p $out/bin
  