(:pep:`456`).
* :ref:`Make newly created file descriptors non-inheritable <whatsnew-pep-446>`
(:pep:`446`) to avoid leaking file descriptors to child processes.
+* New command line option for :ref:`isolated mode <whatsnew-isolated-mode>`,
+ (:issue:`16499`).
+* All modules of the standard library now support server certificate
+ verification including hostname matching (:func:`ssl.match_hostname`) and CRL
+ (Certificate Revocation list, see
+ :func:`ssl.SSLContext.load_verify_locations`).
* A new :func:`hashlib.pbkdf2_hmac` function provides
the `PKCS#5 password-based key derivation function 2
<http://en.wikipedia.org/wiki/PBKDF2>`_.