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<h1 class="page-title">PEP 3111 – Simple input built-in in Python 3000</h1>
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<dl class="rfc2822 field-list simple">
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<dt class="field-odd">Author<span class="colon">:</span></dt>
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<dd class="field-odd">Andre Roberge <andre.roberge at gmail.com></dd>
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<dt class="field-even">Status<span class="colon">:</span></dt>
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<dd class="field-even"><abbr title="Accepted and implementation complete, or no longer active">Final</abbr></dd>
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<dt class="field-odd">Type<span class="colon">:</span></dt>
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<dd class="field-odd"><abbr title="Normative PEP with a new feature for Python, implementation change for CPython or interoperability standard for the ecosystem">Standards Track</abbr></dd>
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<dt class="field-even">Created<span class="colon">:</span></dt>
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<dd class="field-even">13-Sep-2006</dd>
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<dt class="field-odd">Python-Version<span class="colon">:</span></dt>
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<dd class="field-odd">3.0</dd>
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<dt class="field-even">Post-History<span class="colon">:</span></dt>
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<dd class="field-even">22-Dec-2006</dd>
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<details><summary>Table of Contents</summary><ul class="simple">
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<li><a class="reference internal" href="#abstract">Abstract</a></li>
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<li><a class="reference internal" href="#motivation">Motivation</a></li>
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<li><a class="reference internal" href="#rationale">Rationale</a></li>
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<li><a class="reference internal" href="#specification">Specification</a></li>
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<li><a class="reference internal" href="#naming-discussion">Naming Discussion</a></li>
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<li><a class="reference internal" href="#references">References</a></li>
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<li><a class="reference internal" href="#copyright">Copyright</a></li>
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</ul>
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</details></section>
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<section id="abstract">
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<h2><a class="toc-backref" href="#abstract" role="doc-backlink">Abstract</a></h2>
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<p>Input and output are core features of computer programs. Currently,
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Python provides a simple means of output through the print keyword
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and two simple means of interactive input through the input()
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and raw_input() built-in functions.</p>
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<p>Python 3.0 will introduce various incompatible changes with previous
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Python versions (<a class="pep reference internal" href="../pep-3100/" title="PEP 3100 – Miscellaneous Python 3.0 Plans">PEP 3100</a>).
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Among the proposed changes, print will become a built-in
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function, print(), while input() and raw_input() would be removed completely
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from the built-in namespace, requiring importing some module to provide
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even the most basic input capability.</p>
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<p>This PEP proposes that Python 3.0 retains some simple interactive user
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input capability, equivalent to raw_input(), within the built-in namespace.</p>
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<p>It was accepted by the BDFL in December 2006 <a class="footnote-reference brackets" href="#id8" id="id1">[5]</a>.</p>
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</section>
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<section id="motivation">
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<h2><a class="toc-backref" href="#motivation" role="doc-backlink">Motivation</a></h2>
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<p>With its easy readability and its support for many programming styles
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(e.g. procedural, object-oriented, etc.) among others, Python is perhaps
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the best computer language to use in introductory programming classes.
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Simple programs often need to provide information to the user (output)
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and to obtain information from the user (interactive input).
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Any computer language intended to be used in an educational setting should
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provide straightforward methods for both output and interactive input.</p>
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<p>The <a class="pep reference internal" href="../pep-3100/" title="PEP 3100 – Miscellaneous Python 3.0 Plans">current proposals for Python 3.0</a>
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include a simple output pathway
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via a built-in function named print(), but a more complicated method for
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input [e.g. via sys.stdin.readline()], one that requires importing an external
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module. Current versions of Python (pre-3.0) include raw_input() as a
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built-in function. With the availability of such a function, programs that
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require simple input/output can be written from day one, without requiring
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discussions of importing modules, streams, etc.</p>
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</section>
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<section id="rationale">
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<h2><a class="toc-backref" href="#rationale" role="doc-backlink">Rationale</a></h2>
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<p>Current built-in functions, like input() and raw_input(), are found to be
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extremely useful in traditional teaching settings. (For more details,
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see <a class="footnote-reference brackets" href="#id5" id="id2">[2]</a> and the discussion that followed.)
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While the BDFL has clearly stated <a class="footnote-reference brackets" href="#id6" id="id3">[3]</a> that input() was not to be kept in
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Python 3000, he has also stated that he was not against revising the
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decision of killing raw_input().</p>
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<p>raw_input() provides a simple mean to ask a question and obtain a response
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from a user. The proposed plans for Python 3.0 would require the replacement
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of the single statement:</p>
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<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">name</span> <span class="o">=</span> <span class="n">raw_input</span><span class="p">(</span><span class="s2">"What is your name?"</span><span class="p">)</span>
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</pre></div>
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</div>
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<p>by the more complicated:</p>
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<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">sys</span>
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<span class="nb">print</span><span class="p">(</span><span class="s2">"What is your name?"</span><span class="p">)</span>
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<span class="n">same</span> <span class="o">=</span> <span class="n">sys</span><span class="o">.</span><span class="n">stdin</span><span class="o">.</span><span class="n">readline</span><span class="p">()</span>
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</pre></div>
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</div>
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<p>However, from the point of view of many Python beginners and educators, the
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use of sys.stdin.readline() presents the following problems:</p>
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<p>1. Compared to the name “raw_input”, the name “sys.stdin.readline()”
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is clunky and inelegant.</p>
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<p>2. The names “sys” and “stdin” have no meaning for most beginners,
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who are mainly interested in <em>what</em> the function does, and not <em>where</em>
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in the package structure it is located. The lack of meaning also makes
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it difficult to remember:
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is it “sys.stdin.readline()”, or “ stdin.sys.readline()”?
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To a programming novice, there is not any obvious reason to prefer
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one over the other. In contrast, functions simple and direct names like
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print, input, and raw_input, and open are easier to remember.</p>
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<p>3. The use of “.” notation is unmotivated and confusing to many beginners.
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For example, it may lead some beginners to think “.” is a standard
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character that could be used in any identifier.</p>
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<p>4. There is an asymmetry with the print function: why is print not called
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sys.stdout.print()?</p>
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</section>
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<section id="specification">
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<h2><a class="toc-backref" href="#specification" role="doc-backlink">Specification</a></h2>
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<p>The existing <code class="docutils literal notranslate"><span class="pre">raw_input()</span></code> function will be renamed to <code class="docutils literal notranslate"><span class="pre">input()</span></code>.</p>
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<p>The Python 2 to 3 conversion tool will replace calls to <code class="docutils literal notranslate"><span class="pre">input()</span></code> with
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<code class="docutils literal notranslate"><span class="pre">eval(input())</span></code> and <code class="docutils literal notranslate"><span class="pre">raw_input()</span></code> with <code class="docutils literal notranslate"><span class="pre">input()</span></code>.</p>
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</section>
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<section id="naming-discussion">
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<h2><a class="toc-backref" href="#naming-discussion" role="doc-backlink">Naming Discussion</a></h2>
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<p>With <code class="docutils literal notranslate"><span class="pre">input()</span></code> effectively removed from the language,
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the name <code class="docutils literal notranslate"><span class="pre">raw_input()</span></code> makes much less sense and alternatives should be
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considered. The various possibilities mentioned in various forums include:</p>
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<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">ask</span><span class="p">()</span>
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<span class="n">ask_user</span><span class="p">()</span>
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<span class="n">get_string</span><span class="p">()</span>
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<span class="nb">input</span><span class="p">()</span> <span class="c1"># initially rejected by BDFL, later accepted</span>
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<span class="n">prompt</span><span class="p">()</span>
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<span class="n">read</span><span class="p">()</span>
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<span class="n">user_input</span><span class="p">()</span>
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<span class="n">get_response</span><span class="p">()</span>
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</pre></div>
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</div>
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<p>While it was initially rejected by the BDFL, it has been suggested that the
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most direct solution would be to rename “raw_input” to “input” in Python 3000.
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The main objection is that Python 2.x already has a function named “input”,
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and, even though it is not going to be included in Python 3000,
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having a built-in function with the same name but different semantics may
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confuse programmers migrating from 2.x to 3000. Certainly, this is no problem
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for beginners, and the scope of the problem is unclear for more experienced
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programmers, since raw_input(), while popular with many, is not in
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universal use. In this instance, the good it does for beginners could be
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seen to outweigh the harm it does to experienced programmers -
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although it could cause confusion for people reading older books or tutorials.</p>
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<p>The rationale for accepting the renaming can be found here <a class="footnote-reference brackets" href="#id7" id="id4">[4]</a>.</p>
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</section>
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<section id="references">
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<h2><a class="toc-backref" href="#references" role="doc-backlink">References</a></h2>
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<aside class="footnote-list brackets">
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<aside class="footnote brackets" id="id5" role="doc-footnote">
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<dt class="label" id="id5">[<a href="#id2">2</a>]</dt>
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<dd>The fate of raw_input() in Python 3000
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<a class="reference external" href="https://mail.python.org/pipermail/edu-sig/2006-September/006967.html">https://mail.python.org/pipermail/edu-sig/2006-September/006967.html</a></aside>
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<aside class="footnote brackets" id="id6" role="doc-footnote">
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<dt class="label" id="id6">[<a href="#id3">3</a>]</dt>
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<dd>Educational aspects of Python 3000
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<a class="reference external" href="https://mail.python.org/pipermail/python-3000/2006-September/003589.html">https://mail.python.org/pipermail/python-3000/2006-September/003589.html</a></aside>
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<aside class="footnote brackets" id="id7" role="doc-footnote">
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<dt class="label" id="id7">[<a href="#id4">4</a>]</dt>
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<dd>Rationale for going with the straight renaming
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<a class="reference external" href="https://mail.python.org/pipermail/python-3000/2006-December/005249.html">https://mail.python.org/pipermail/python-3000/2006-December/005249.html</a></aside>
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<aside class="footnote brackets" id="id8" role="doc-footnote">
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<dt class="label" id="id8">[<a href="#id1">5</a>]</dt>
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<dd>BDFL acceptance of the PEP
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<a class="reference external" href="https://mail.python.org/pipermail/python-3000/2006-December/005257.html">https://mail.python.org/pipermail/python-3000/2006-December/005257.html</a></aside>
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</aside>
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</section>
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<section id="copyright">
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<h2><a class="toc-backref" href="#copyright" role="doc-backlink">Copyright</a></h2>
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<p>This document has been placed in the public domain.</p>
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</section>
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</section>
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<hr class="docutils" />
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<p>Source: <a class="reference external" href="https://github.com/python/peps/blob/main/peps/pep-3111.rst">https://github.com/python/peps/blob/main/peps/pep-3111.rst</a></p>
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<p>Last modified: <a class="reference external" href="https://github.com/python/peps/commits/main/peps/pep-3111.rst">2023-09-09 17:39:29 GMT</a></p>
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</article>
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<h2>Contents</h2>
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<ul>
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<li><a class="reference internal" href="#abstract">Abstract</a></li>
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<li><a class="reference internal" href="#motivation">Motivation</a></li>
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<li><a class="reference internal" href="#rationale">Rationale</a></li>
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<li><a class="reference internal" href="#specification">Specification</a></li>
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<li><a class="reference internal" href="#naming-discussion">Naming Discussion</a></li>
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<li><a class="reference internal" href="#references">References</a></li>
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<li><a class="reference internal" href="#copyright">Copyright</a></li>
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</ul>
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<br>
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<a id="source" href="https://github.com/python/peps/blob/main/peps/pep-3111.rst">Page Source (GitHub)</a>
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