title: asgiref AsyncToSync explanation
body: <pre><code># https://github.com/django/asgiref/blob/master/asgiref/sync.py
  class AsyncToSync:
      """
      Utility class which turns an awaitable that only works on the thread with
      the event loop into a synchronous callable that works in a subthread.
  
      If the call stack contains an async loop, the code runs there.
      Otherwise, the code runs in a new loop in a new thread.
      
      ###############  DON'T UNDERSTAND ####################
      Either way, this thread then <b>pauses and waits to run any thread_sensitive
      code called from further down the call stack using SyncToAsync</b>, before
      finally exiting once the async task returns.
      """
  </code></pre>
  <p>Can anyone help to explain the bolded text? thanks in advance!</p>