code: function _setSessionReferrer(){
  
      if (document.referrer){
  
          sessionReferrer = document.referrer;
          const oldReferrer = utils.getCookie(constants.referrerCookieName);
  
          return oldReferrer != document.referrer;
  
      }
  
  }
docs: private functions 
  @private
  @memberof SessionManager
  return true if a new session is necessary to create because of a change in referrer