Add `show_group` param to `traceback.format_exception_only` function

[sobolevn]

Feature or enhancement

This function does not have this param:

cpython/Lib/traceback.py

Lines 151 to 166 in 7f9a99e

	def format_exception_only(exc, /, value=_sentinel):
	"""Format the exception part of a traceback.
	The return value is a list of strings, each ending in a newline.
	The list contains the exception's message, which is
	normally a single string; however, for :exc:`SyntaxError` exceptions, it
	contains several lines that (when printed) display detailed information
	about where the syntax error occurred. Following the message, the list
	contains the exception's ``__notes__``.
	"""
	if value is _sentinel:
	value = exc
	te = TracebackException(type(value), value, None, compact=True)
	return list(te.format_exception_only())

While the format_exception_only method of TracebackException does have this param. So, in order to proceed with #104150 I need this function to give me ExceptionGroup information.

I have a PR ready.

Linked PRs

• gh-111388: Add show_group to traceback.format_exception_only #111390