Write `fetch_all(urls)` that spawns one `threading.Thread` per URL, has each thread store `f"fetched {url}"` into a shared results list at its index, joins all threads, and returns the results list in the original order.
Required in your answer: threading.Thread.join(
Runs via Pyodide
import threading
def fetch_all(urls):
results = [None] * len(urls)
# TODO: spawn a thread per url, join them, fill results
return results
