In the documentation for the `traceback` module, the definitions of functions `extract_tb` [0], `format_list` [1] and classmethod `from_list` [2] mention the old style (4-)tuples that these functions used to return or accept.

Since Python 3.5, however, they return or accept a FrameSummary object instead of the 4-tuple, or a StackSummary object instead of a list of 4-tuples.

I'm including a patch that fixes these definitions to make them reflect the new reality.

[0] https://docs.python.org/3.6/library/traceback.html#traceback.extract_tb
[1] https://docs.python.org/3.6/library/traceback.html#traceback.format_list
[2] https://docs.python.org/3.6/library/traceback.html#traceback.StackSummary.from_list