Consider adding decorator for required inner class

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-05-23.23:07:34.328>
labels = ['type-feature', 'library']
title = 'Consider adding decorator for required inner class'
updated_at = <Date 2020-05-23.23:07:34.328>
user = 'https://github.com/erip'

bugs.python.org fields:

activity = <Date 2020-05-23.23:07:34.328>
actor = 'Elijah Rippeth'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2020-05-23.23:07:34.328>
creator = 'Elijah Rippeth'
dependencies = []
files = []
hgrepos = []
issue_num = 40749
keywords = []
message_count = 1.0
messages = ['369756']
nosy_count = 1.0
nosy_names = ['Elijah Rippeth']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue40749'
versions = []