anchor.diff:  
   let 
   
  -  inherit (config.services.vsftpd) anonymousUser writeEnable anonymousUploadEnable anonymousMkdirEnable;
  +  inherit (config.services.vsftpd) anonymousUser localUsers writeEnable anonymousUploadEnable anonymousMkdirEnable;
     inherit (pkgs) vsftpd;
   
     yesNoOption = p : name :
  
positive.code:           default = false;
            description = "
              Whether to enable the anonymous FTP user.
            ";
          };
  
  
negative.code:         start script
          cat > /etc/vsftpd.conf <<EOF
          ${yesNoOption anonymousUser "anonymous_enable"}
          ${yesNoOption localUsers "local_enable"}
          ${yesNoOption writeEnable "write_enable"}
          ${yesNoOption anonymousUploadEnable "anon_upload_enable"}
          ${yesNoOption anonymousMkdirEnable "anon_mkdir_write_enable"}
  