code: function completeOutstandingRequest(fn) {
      try {
        fn.apply(null, sliceArgs(arguments, 1));
      } finally {
        outstandingRequestCount--;
        if (outstandingRequestCount === 0) {
          while (outstandingRequestCallbacks.length) {
            try {
              outstandingRequestCallbacks.pop()();
            } catch (e) {
              $log.error(e);
            }
          }
        }
      }
    }
docs: Executes the `fn` function(supports currying) and decrements the `outstandingRequestCallbacks`
  counter. If the counter reaches 0, all the `outstandingRequestCallbacks` are executed.