[docs] [issue27242] Clarify the use cases of NotImplemented in the docs

[Emanuel Barry]

New submission from Emanuel Barry:

The NotImplemented docs aren't explicit enough when it comes to where it can/should be used. Patch attached.

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assignee: docs at python
components: Documentation
files: NotImplemented_wording_1.patch
keywords: patch
messages: 267543
nosy: docs at python, ebarry
priority: normal
severity: normal
stage: patch review
status: open
title: Clarify the use cases of NotImplemented in the docs
type: enhancement
versions: Python 3.6
Added file: http://bugs.python.org/file43263/NotImplemented_wording_1.patch

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue27242>
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