public static RequestManager with(FragmentActivity activity) {
        RequestManagerRetriever retriever = RequestManagerRetriever.get();
        return retriever.get(activity);
    }
Begin a load with Glide that will tied to the give {@link FragmentActivity}'s lifecycle
and that uses the given {@link FragmentActivity}'s default options.

@param activity The activity to use.
@return A RequestManager for the given FragmentActivity that can be used to start a load.
core/src/main/java/com/bumptech/glide/Glide.java