#305: add mfa step during auth

flow-typed/Promise.js

@@ -0,0 +1,29 @@
+/**
+ * This is a copypasted declaration from
+ * https://github.com/facebook/flow/blob/master/lib/core.js
+ * with addition of finally method
+ */
+declare class Promise<+R> {
+    constructor(callback: (
+      resolve: (result: Promise<R> | R) => void,
+      reject:  (error: any) => void
+    ) => mixed): void;
+
+    then<U>(
+      onFulfill?: (value: R) => Promise<U> | U,
+      onReject?: (error: any) => Promise<U> | U
+    ): Promise<U>;
+
+    catch<U>(
+      onReject?: (error: any) => Promise<U> | U
+    ): Promise<R | U>;
+
+    static resolve<T>(object: Promise<T> | T): Promise<T>;
+    static reject<T>(error?: any): Promise<T>;
+    static all<Elem, T:Iterable<Elem>>(promises: T): Promise<$TupleMap<T, typeof $await>>;
+    static race<T, Elem: Promise<T> | T>(promises: Array<Elem>): Promise<T>;
+
+    finally<T>(
+      onSettled?: ?(value: any) => Promise<T> | T
+    ): Promise<T>;
+}