bpo-35838: document optionxform must be idempotent by methane · Pull Request #12656 · python/cpython

Expand Up @@ -721,6 +721,12 @@ be overridden by subclasses or by attribute assignment. >>> list(custom['Section2'].keys()) ['AnotherKey']
.. note:: The optionxform function transforms option names to a canonical form. This should be an idempotent function: if the name is already in canonical form, it should be returned unchanged.

.. attribute:: ConfigParser.SECTCRE
A compiled regular expression used to parse section headers. The default Expand Down