json.dumps to check for obj.__json__ before raising TypeError

GitHub fields:

assignee = 'https://github.com/etrepum'
closed_at = None
created_at = <Date 2016-06-21.13:09:18.565>
labels = ['3.7', 'type-feature', 'library']
title = 'json.dumps to check for obj.__json__ before raising TypeError'
updated_at = <Date 2018-02-01.16:33:45.801>
user = 'https://bugs.python.org/DanielWard'

bugs.python.org fields:

activity = <Date 2018-02-01.16:33:45.801>
actor = 'ulope'
assignee = 'bob.ippolito'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2016-06-21.13:09:18.565>
creator = 'Daniel Ward'
dependencies = []
files = ['46701']
hgrepos = []
issue_num = 27362
keywords = ['patch']
message_count = 11.0
messages = ['268991', '268993', '268995', '268999', '269002', '269003', '269021', '269091', '289001', '289006', '289007']
nosy_count = 10.0
nosy_names = ['rhettinger', 'bob.ippolito', 'steven.daprano', 'r.david.murray', 'berker.peksag', 'serhiy.storchaka', 'abarry', 'ulope', 'Daniel Ward', 'Ollie Ford']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue27362'
versions = ['Python 3.7']