Issue19995: fixed typo; switched from test.support.check_warnings to assertWarns
Issue #20196: Fixed a bug where Argument Clinic did not generate correct
parsing code for functions with positional-only parameters where all arguments
are optional.
Issue #20214: Fixed a number of small issues and documentation errors in
Argument Clinic (see issue for details).
Minor doc fix in Clinic howto.
Issue #20228: Argument Clinic now has special support for class special
methods.
Issue #19082: Working xmlrpc.server and xmlrpc.client examples. Both in modules and in documentation.
merge from 3.3

Issue #19082: Working xmlrpc.server and xmlrpc.client examples. Both in modules and in documentation.