PEP 789: minor clarifications

peps/pep-0789.rst

@@ -645,11 +645,9 @@ yield-within-with problems are not exclusive to async generators:
             yield
 
     one = decimal.Decimal(1)
-    x = one / 3
+    print(one / 3)  # 0.3333333333333333333333333333
     next(gen := why_would_you_do_this())
-    y = one / 3
-    print(x)  # 0.3333333333333333333333333333
-    print(y)  # 0.3
+    print(one / 3)  # 0.3
 
 
 While I've had good experiences in async Python without async generators
@@ -680,13 +678,15 @@ concurrency is that your stack becomes a tree, with child tasks encapsulated
 within some parent frame.  They're extending the basic structured programming
 model in different, and unfortunately incompatible, directions.
 
-Note that ``TaskGroup`` *would* play nicely with generators if suspending the
-frame with the context manager also suspended all child tasks.  Note also that
-this would cause all of our motivating examples to deadlock, as we wait for
-values to be produced by suspended child tasks - a prohibitive design problem.
+Suppose for example that suspending a frame containing an open ``TaskGroup``
+also suspended all child tasks.  This would preserve the 'downward' structured
+concurrency, in that children remain encapsulated - albeit at the cost of
+deadlocking both of our motivating examples, and much real-world code.
+However, it would still be possible to resume the generator in a different
+task, violating the 'upwards' invariant of structured concurrency.
 
 We don't think it's worth adding this much machinery to handle cancel scopes,
-while leaving task groups (and no-exception cases) broken.
+while still leaving task groups broken.
 
 
 Alternative implementation - inspecting bytecode