Retrieve a course's block tree with per-block student view data using the Open edX Course Blocks API

Steps

1. Call the Course Blocks API for a course/root usage key, passing the username of the learner whose personalized view you want, or omitting it for a staff/anonymous view.
2. Use the depth parameter to control how many levels of the block tree are returned, or pass all to retrieve the full tree in one call.
3. Pass a comma-separated block_counts parameter listing block types (e.g. video) to get an aggregate count of that block type under each returned block and its descendants.
4. Pass a student_view_data parameter listing block types whose rendering-ready JSON payload you want included; only the block types you list there get student_view_data populated in the response.
5. Combine block_counts and student_view_data in a single request when you need both counts and payloads for the same block type, instead of issuing separate calls.