How to handle external blockwise of large files

I'd like to second the feature request to be able to service blockwise GET without the 65K limitation (or also, the limitation of needing to put the entire resource into RAM).

I understand how to use external_blockwise_store flag in the M2MResource constructor, and set_outgoing_block_message_callback, to handle storing a resource externally.

But I'd like an example (maybe by overriding "handle_get_request?") of how to serve up a file one block at a time.  Or a feature added to mbed-client to do this.