improve docs

Co-authored-by: Andreas Klöckner <inform@tiker.net>

arraycontext/container/__init__.py

@@ -125,7 +125,7 @@ def serialize_container(ary: ArrayContainer) -> Iterable[Tuple[Any, Any]]:
     the control of the container class. However, the order is required to be
     deterministic, i.e. two calls to :func:`serialize_container` on
     array containers of the same types with the same number of
-    sub-arrays should result in an iterable with the keys in the same
+    sub-arrays must result in an iterable with the keys in the same
     order.
 
     If *ary* is mutable, the serialization function is not required to ensure

arraycontext/container/traversal.py

@@ -554,7 +554,7 @@ def flatten(ary: ArrayOrContainerT, actx: ArrayContext) -> Any:
 def unflatten(
         template: ArrayOrContainerT, ary: Any,
         actx: ArrayContext) -> ArrayOrContainerT:
-    """Unflatten an array produced by :func:`flatten` back into an
+    """Unflatten an array *ary* produced by :func:`flatten` back into an
     :class:`~arraycontext.ArrayContainer`.
 
     The order and sizes of each slice into *ary* are determined by the