How to use the karma.stopper.stop function in karma

return new Promise(resolve => {
      if (this.karmaEventListener.isServerLoaded) {
        const stopper = require("karma").stopper;
        stopper.stop({ port: 9876 }, (exitCode: number) => {
          this.logger.info(`Karma exited succesfully`);
          resolve();
          this.karmaEventListener.stopListeningToKarma();
        });
      }
    });
  }

return new Promise(resolve => {
      const stopper = require("karma").stopper;
      stopper.stop({ port: 9876 }, (exitCode: any) => {
        resolve();
      });
    });
  }

public stop(): void {
    if (this.karmaEventListener.isServerLoaded) {
      const stopper = require("karma").stopper;
      stopper.stop({ port: 9876 }, (exitCode: number) => {
        this.logger.info(`Karma exited succesfully`);
      });
      this.karmaEventListener.stopListeningToKarma();
    }
  }

      process.once('exit', () => stopper.stop({}));
      process.once('SIGINT', () => process.exit());