Set the available ciphers for sockets created with this context.
It should be a string in the `OpenSSL cipher list format
- <https://wiki.openssl.org/index.php/Manual:Ciphers(1)#CIPHER_LIST_FORMAT>`_.
+ <https://www.openssl.org/docs/manmaster/man1/ciphers.html>`_.
If no cipher can be selected (because compile-time options or other
configuration forbids use of all the specified ciphers), an
:class:`SSLError` will be raised.
Darren Worrall
Thomas Wouters
Daniel Wozniak
+Marcin Niemira
Wei Wu
Heiko Wundram
Doug Wyatt