anchor.diff:      self_ = with self; helperFunctions // {
   
     # Make some arguments passed to all-packages.nix available
  -  inherit system platform;
  +  targetSystem =
  +    if args.targetSystem != null then
  +      throw "We don't support setting target systems yet."
  +    else
  +      builtins.currentSystem;
  +  hostSystem =
  +    if args.hostSystem != null then
  +      throw "We don't support setting the host system yet."
  +    else
  +      builtins.currentSystem;
   
     # Allow callPackage to fill in the pkgs argument
     inherit pkgs;
  
positive.code: ################################################################################
  ################################################################################
  ################################################################################
  ################################BEGIN ALL PKGS##################################
  ################################################################################
  ################################################################################
  ################################################################################
  
negative.code:    platform. */
  
  
  { targetSystem ? null
  , hostSystem ? null
  
  # Allow a configuration attribute set to be passed in as an
  # argument.  Otherwise, it's read from $NIXPKGS_CONFIG or
  # ~/.nixpkgs/config.nix.
  , configFunction ? null
  } @ args:
  
  let
  
    # The contents of the configuration file found at $NIXPKGS_CONFIG or
    # $HOME/.nixpkgs/config.nix.
    # for NIXOS (nixos-rebuild): use nixpkgs.config option
    config =
      if args.configFunction != null then
        args.configFunction { inherit pkgs; }
      else
        let
          configFiles = [
            (builtins.getEnv "NIXPKGS_CONFIG")
            ((builtins.getEnv "HOME") + "/.nixpkgs/config.nix")
          ];
          configFilePaths = map builtins.toPath configFiles;
          existingConfigFiles = filter builtins.pathExists configFilePaths;
        in
          import (head existingConfigFiles) { inherit pkgs; };
  
    # Helper functions that are exported through `pkgs'.
    helperFunctions =
  