subclassing of :class:`~inspect.Signature` easier (contributed
by Yury Selivanov and Eric Snow in :issue:`17373`).
+ipaddress
+---------
+
+* :class:`ipaddress.IPv4Network` and :class:`ipaddress.IPv6Network` now
+ accept an ``(address, netmask)`` tuple argument, so as to easily construct
+ network objects from existing addresses (contributed by Peter Moody
+ and Antoine Pitrou in :issue:`16531`).
+
signal
------
data) for large objects. ``calloc()`` is used instead of ``malloc()`` to
allocate memory for these objects.
+* Some operations on :class:`~ipaddress.IPv4Network` and
+ :class:`~ipaddress.IPv6Network` have been massively sped up, such as
+ :meth:`~ipaddress.IPv4Network.subnets`, :meth:`~ipaddress.IPv4Network.supernet`,
+ :func:`~ipaddress.summarize_address_range`, :func:`~ipaddress.collapse_addresses`.
+ The speed up can range from 3x to 15x.
+ (:issue:`21486`, :issue:`21487`, :issue:`20826`)
+
Build and C API Changes
=======================