/**
  * Performs any type of http request. First argument is required, and can either be a url or
  * a {@link Request} instance. If the first argument is a url, an optional {@link RequestOptions}
  * object can be provided as the 2nd argument. The options object will be merged with the values
  * of {@link BaseRequestOptions} before performing the request.
  */
 request(url: string | Request, options?: RequestOptionsArgs): Observable<Response> {
   var responseObservable: any;
   if (isString(url)) {
     url = new Request(mergeOptions(this._defaultOptions, options, RequestMethod.Get, url));
   }
   if (url instanceof Request) {
     if (url.method !== RequestMethod.Get) {
       makeTypeError('JSONP requests must use GET request method.');
     }
     responseObservable = httpRequest(this._backend, url);
   } else {
     throw makeTypeError('First argument must be a url string or Request instance.');
   }
   return responseObservable;
 }

export function normalizeMethodName(method): RequestMethods {
  if (isString(method)) {
    var originalMethod = method;
    method = method.replace(/(\w)(\w*)/g, (g0, g1, g2) => g1.toUpperCase() + g2.toLowerCase());
    method = RequestMethods[method];
    if (typeof method !== 'number')
      throw makeTypeError(
          `Invalid request method. The method "${originalMethod}" is not supported.`);
  }
  return method;
}