docs: function XAPIWrapper(config) {
      if (!config) {
          throw new Error("config was not defined");
      }
  
      if (!config.url) {
          throw new Error("config.url was not defined");
      }
  
      if (!config.auth) {
          throw new Error("config.auth was not defined");
      }
  
      if (!((config.auth.user || config.auth.username) && (config.auth.pass || config.auth.password))) {
          throw new Error("config.auth does not have user or pass");
      }
  
      this.config = config;
  }