code: function set(my, res, lang) {
  
    return res.cookie(my.cookie, lang, {
      domain: my.domain,
      path: my.path,
      maxAge: my.maxAge,
      httpOnly: my.httpOnly,
      secure: my.secure,
      signed: my.signed
    }), lang;
  }
docs: /*
  functions
   
  set language to cookie
  
  @function set
  @param {Object} my - user option
  @param {Object} res - response to client
  @param {String} lang - string for cookie
  @return {String}