anchor.diff:          echo "https://github.com/NixOS/nixpkgs/archive/''${@:-master}.tar.gz"
       }
   
  -    pr-darwin() {
  -        local pr=$1
  -        shift 1
  -        rev-darwin "$(curl "https://api.github.com/repos/LnL7/nix-darwin/pulls/$pr/commits" | jq -r '.[-1].sha')"
  -    }
  -
       pr-nixpkgs() {
           local pr=$1
           shift 1
  
positive.code:     PS1='%F{red}%B%(?..%? )%b%f%# '
      RPS1='$(_prompt_nix)%F{green}%~%f'
  
      if [ -z "$IN_NIX_SANDBOX" ]; then
        PS1+='%F{red}[no-sandbox]%f '
      fi
    '';
  
  
negative.code:   environment.darwinConfig = "$HOME/.config/nixpkgs/darwin/configuration.nix";
  
    nix.nixPath =
      [{ # Use local nixpkgs checkout instead of channels.
        darwin-config = "$HOME/.config/nixpkgs/darwin/configuration.nix";
        darwin = "$HOME/.nix-defexpr/darwin"; }
      ];
  
    nixpkgs.config.allowUnfree = true;
  