code: function Selenium(options) {
  
    if (!options) {
      throw new Error('options is required');
    }
  
    if (booleanHelper.isFalsey(options.port)) {
      throw new Error('options.port is required');
    }
  
    this.options = _.clone(options);
  
    this.seleniumStandaloneOptions = options.seleniumStandaloneOptions;
  
    if (!this.options['clean-selenium-server']) {
      // poor-man's singleton is enough for our needs
      if (typeof Selenium.instance === 'object') {
        log.debug('[chimp][selenium]', 'Selenium object already exists, not creating a new one');
        return Selenium.instance;
      }
      log.debug('[chimp][selenium]', 'Selenium object created');
      Selenium.instance = this;
    }
  
    this.options.port = String(options.port);
    this.child = null;
  }
docs: Selenium Constructor
  
  @param {Object} options
  @api public