Issue #24400: Mention that __instancecheck__ is used in abc.Awaitable and Coroutine
diff --git a/Doc/conf.py b/Doc/conf.py
index 28dd80f..20086a9 100644
--- a/Doc/conf.py
+++ b/Doc/conf.py
@@ -44,7 +44,7 @@
# -----------------------
# Use our custom theme.
-html_theme = 'pydoctheme'
+html_theme = 'classic'
html_theme_path = ['tools']
html_theme_options = {'collapsiblesidebar': True}
diff --git a/Doc/library/collections.abc.rst b/Doc/library/collections.abc.rst
index 0653d4e..dc2704e 100644
--- a/Doc/library/collections.abc.rst
+++ b/Doc/library/collections.abc.rst
@@ -161,6 +161,12 @@
:term:`Coroutine` objects and instances of the
:class:`~collections.abc.Coroutine` ABC are all instances of this ABC.
+ .. note::
+ In CPython, generator-based coroutines are *awaitables*, even though
+ they do not have an :meth:`__await__` method. This ABC
+ implements an :meth:`~class.__instancecheck__` method to make them
+ instances of itself.
+
.. versionadded:: 3.5
.. class:: Coroutine
@@ -172,6 +178,12 @@
:meth:`__await__`. All :class:`Coroutine` instances are also instances of
:class:`Awaitable`. See also the definition of :term:`coroutine`.
+ .. note::
+ In CPython, generator-based coroutines are *awaitables* and *coroutines*,
+ even though they do not have an :meth:`__await__` method. This ABC
+ implements an :meth:`~class.__instancecheck__` method to make them
+ instances of itself.
+
.. versionadded:: 3.5
.. class:: AsyncIterable