Document exception chaining #47363

assignee = 'https://github.com/birkenfeld'
closed_at = <Date 2008-07-19.15:51:45.928>
created_at = <Date 2008-06-14.20:31:52.683>
labels = ['docs']
title = 'Document exception chaining'
updated_at = <Date 2008-07-19.15:51:45.922>
user = 'https://github.com/benjaminp'

activity = <Date 2008-07-19.15:51:45.922>
actor = 'georg.brandl'
assignee = 'georg.brandl'
closed = True
closed_date = <Date 2008-07-19.15:51:45.928>
closer = 'georg.brandl'
components = ['Documentation']
creation = <Date 2008-06-14.20:31:52.683>
creator = 'benjamin.peterson'
dependencies = []
files = []
hgrepos = []
issue_num = 3113
keywords = []
message_count = 2.0
messages = ['68215', '70041']
nosy_count = 3.0
nosy_names = ['georg.brandl', 'pitrou', 'benjamin.peterson']
pr_nums = []
priority = 'critical'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue3113'
versions = ['Python 3.0']