Flip a last `MultiError` to a beg, add todo on `@stream` func

tests/test_context_stream_semantics.py

@@ -246,10 +246,10 @@ def test_simple_context(
             trio.run(main)
         except error_parent:
             pass
-        except trio.MultiError as me:
+        except BaseExceptionGroup as beg:
             # XXX: on windows it seems we may have to expect the group error
             from tractor._exceptions import is_multi_cancelled
-            assert is_multi_cancelled(me)
+            assert is_multi_cancelled(beg)
     else:
         trio.run(main)
 

tests/test_legacy_one_way_streaming.py

@@ -38,10 +38,13 @@ async def async_gen_stream(sequence):
     assert cs.cancelled_caught
 
 
+# TODO: deprecated either remove entirely
+# or re-impl in terms of `MsgStream` one-sides
+# wrapper, but at least remove `Portal.open_stream_from()`
 @tractor.stream
 async def context_stream(
     ctx: tractor.Context,
-    sequence
+    sequence: list[int],
 ):
     for i in sequence:
         await ctx.send_yield(i)