code: function(access_token, expires_at) {
  		if (!access_token) return Promise.reject(new Error('wotblitz.auth.prolongate: access_token is required'));
  
  		return request({
  			hostname: hosts.wot,
  			path: '/wot/auth/prolongate/'
  		}, {
  			access_token: access_token,
  			expires_at: expires_at || 14 * 24 * 60 * 60 // 14 days in seconds
  		});
  	}
docs: Access token extension
  
  @param {string} access_token user's authentication string
  @param {number} [expires_at] date or time span of expiration (default: 14 days)
  @returns {Promise<Object>} resolves to the new token and related information