code: function createSession(){
  
      // can also check if any ealier session can be used
      if (!currentSession){
          
          const createNewSession = _setSessionReferrer();
          const currentSessionCookie = utils.getCookie(constants.sessionCookieName);
  
          if (currentSessionCookie && !createNewSession){
  
              const currentSessionSplit = currentSessionCookie.split('__');
              currentSession = new session(currentSessionSplit[0], 
                  parseInt(currentSessionSplit[1]), {});
              
              logger.debug('Found existing session', currentSessionSplit[0], 
                  currentSessionSplit[1]);
  
          } else{
  
              currentSession = new session(null, null, {});
              setSessionCookie();
  
              logger.debug('Creating new session', currentSession.getSessionToken(), 
                  currentSession.getSessionUnixTime());
  
          }
  
          // associate session referrer with the session
          if (sessionReferrer){
  
              currentSession.setExtra('referrer', sessionReferrer);
              
          }
          
      }
  
      return currentSession;
  
  }
docs: Manages creation of current session.
  @memberof DataManager
  @private