forEach(fn) {
    utils$1.forEach(this.handlers, function forEachHandler(h) {
      if (h !== null) {
        fn(h);
      }
    });
  }
Iterate over all the registered interceptors

This method is particularly useful for skipping over any
interceptors that may have become `null` calling `eject`.

@param {Function} fn The function to call for each interceptor

@returns {void}