Missing definition of frozen module

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-08-17.10:55:00.981>
labels = ['type-feature', '3.7', 'docs']
title = 'Missing definition of frozen module'
updated_at = <Date 2017-08-17.10:55:00.981>
user = 'https://github.com/marco-buttu'

bugs.python.org fields:

activity = <Date 2017-08-17.10:55:00.981>
actor = 'marco.buttu'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2017-08-17.10:55:00.981>
creator = 'marco.buttu'
dependencies = []
files = []
hgrepos = []
issue_num = 31224
keywords = []
message_count = 1.0
messages = ['300405']
nosy_count = 2.0
nosy_names = ['docs@python', 'marco.buttu']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue31224'
versions = ['Python 3.7']