code: function Call(mediaPipeline) {
    // always initialize all instance properties
    this.mediaPipeline = mediaPipeline;
    this.participants = {};
    this.callId = shortid.generate();
    this.callerId = null; // the first caller who initiate this call session
  
    logger.info('CALL ' + this.callId + ' has been created.');
  }
docs: Constructor