anchor.diff:  
         promptInit = mkOption {
           default = ''
  +          # Note that to manually override this in ~/.zshrc you should run `prompt off`
  +          # before setting your PS1 and etc. Otherwise this will likely to interact with
  +          # your ~/.zshrc configuration in unexpected ways as the default prompt sets
  +          # a lot of different prompt variables.
             autoload -U promptinit && promptinit && prompt walters && setopt prompt_sp
           '';
           description = ''
  
positive.code:       ''
          # /etc/zprofile: DO NOT EDIT -- this file has been generated automatically.
          # This file is read for login shells.
  
          # Only execute this file once per shell.
          if [ -n "$__ETC_ZPROFILE_SOURCED" ]; then return; fi
          __ETC_ZPROFILE_SOURCED=1
  
          ${cfge.loginShellInit}
  
          ${cfg.loginShellInit}
  
negative.code: 
          HELPDIR="${pkgs.zsh}/share/zsh/$ZSH_VERSION/help"
  
          # Tell zsh how to find installed completions.
          for p in ''${(z)NIX_PROFILES}; do
              fpath+=($p/share/zsh/site-functions $p/share/zsh/$ZSH_VERSION/functions $p/share/zsh/vendor-completions)
          done
  
          # Setup custom shell init stuff.
          ${cfge.shellInit}
  
          ${cfg.shellInit}
  