Include simple file loading and saving functions in JSON standard library.

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-03-10.02:05:40.350>
labels = ['type-feature', 'library']
title = 'Include simple file loading and saving functions in JSON standard library.'
updated_at = <Date 2021-03-10.03:56:35.985>
user = 'https://bugs.python.org/nervecenter'

bugs.python.org fields:

activity = <Date 2021-03-10.03:56:35.985>
actor = 'methane'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-03-10.02:05:40.350>
creator = 'nervecenter'
dependencies = []
files = []
hgrepos = []
issue_num = 43457
keywords = []
message_count = 3.0
messages = ['388403', '388404', '388406']
nosy_count = 2.0
nosy_names = ['methane', 'nervecenter']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue43457'
versions = []