Expose importlib.util.set___package__.
diff --git a/Doc/library/importlib.rst b/Doc/library/importlib.rst
index dc015c7..4a0ff0e 100644
--- a/Doc/library/importlib.rst
+++ b/Doc/library/importlib.rst
@@ -167,20 +167,28 @@
A :term:`decorator` for a :term:`loader` which handles selecting the proper
module object to load with. The decorated method is expected to have a call
signature of ``method(self, module_object)`` for which the second argument
- will be the module object to be used (note that the decorator will not work
- on static methods because of the assumption of two arguments).
+ will be the module object to be used by the loader (note that the decorator
+ will not work on static methods because of the assumption of two
+ arguments).
The decorated method will take in the name of the module to be loaded as
- normal. If the module is not found in :data:`sys.modules` then a new one is
- constructed with its :attr:`__name__` attribute set. Otherwise the module
- found in :data:`sys.modules` will be passed into the method. If an
+ expected for a :term:`loader`. If the module is not found in
+ :data:`sys.modules` then a new one is constructed with its
+ :attr:`__name__` attribute set. Otherwise the module found in
+ :data:`sys.modules` will be passed into the method. If an
exception is raised by the decorated method and a module was added to
:data:`sys.modules` it will be removed to prevent a partially initialized
- module from being in left in :data:`sys.modules` If an exception is raised
- by the decorated method and a module was added to :data:`sys.modules` it
- will be removed to prevent a partially initialized module from being in
- left in :data:`sys.modules`. If the module was already in
- :data:`sys.modules` then it is left alone.
+ module from being in left in :data:`sys.modules`. If the module was already
+ in :data:`sys.modules` then it is left alone.
- Use of this decorator handles all the details of what module a loader
- should use as specified by :pep:`302`.
+ Use of this decorator handles all the details of what module object a
+ loader should initialize as specified by :pep:`302`.
+
+
+.. function:: set___package__(method)
+
+ A :term:`decorator` for a :term:`loader` to set the :attr:`__package__`
+ attribute on the module returned by the loader. If :attr:`__package__` is
+ set and has a value other than :keyword:`None` it will not be changed.
+ Note that the module returned by the loader is what has the attribute
+ set on and not the module found in :data:`sys.modules`.