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269 lines
9.8 KiB
ReStructuredText
269 lines
9.8 KiB
ReStructuredText
This is Python version 3.8.0 alpha 2
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====================================
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.. image:: https://travis-ci.org/python/cpython.svg?branch=master
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:alt: CPython build status on Travis CI
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:target: https://travis-ci.org/python/cpython
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.. image:: https://ci.appveyor.com/api/projects/status/4mew1a93xdkbf5ua/branch/master?svg=true
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:alt: CPython build status on Appveyor
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:target: https://ci.appveyor.com/project/python/cpython/branch/master
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.. image:: https://dev.azure.com/python/cpython/_apis/build/status/Azure%20Pipelines%20CI?branchName=master
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:alt: CPython build status on Azure DevOps
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:target: https://dev.azure.com/python/cpython/_build/latest?definitionId=4&branchName=master
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.. image:: https://codecov.io/gh/python/cpython/branch/master/graph/badge.svg
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:alt: CPython code coverage on Codecov
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:target: https://codecov.io/gh/python/cpython
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.. image:: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg
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:alt: Python Zulip chat
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:target: https://python.zulipchat.com
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Copyright (c) 2001-2019 Python Software Foundation. All rights reserved.
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See the end of this file for further copyright and license information.
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.. contents::
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General Information
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-------------------
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- Website: https://www.python.org
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- Source code: https://github.com/python/cpython
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- Issue tracker: https://bugs.python.org
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- Documentation: https://docs.python.org
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- Developer's Guide: https://devguide.python.org/
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Contributing to CPython
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-----------------------
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For more complete instructions on contributing to CPython development,
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see the `Developer Guide`_.
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.. _Developer Guide: https://devguide.python.org/
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Using Python
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------------
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Installable Python kits, and information about using Python, are available at
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`python.org`_.
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.. _python.org: https://www.python.org/
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Build Instructions
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------------------
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On Unix, Linux, BSD, macOS, and Cygwin::
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./configure
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make
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make test
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sudo make install
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This will install Python as ``python3``.
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You can pass many options to the configure script; run ``./configure --help``
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to find out more. On macOS and Cygwin, the executable is called ``python.exe``;
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elsewhere it's just ``python``.
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If you are running on macOS with the latest updates installed, make sure to install
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openSSL or some other SSL software along with Homebrew or another package manager.
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If issues persist, see https://devguide.python.org/setup/#macos-and-os-x for more
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information.
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On macOS, if you have configured Python with ``--enable-framework``, you
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should use ``make frameworkinstall`` to do the installation. Note that this
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installs the Python executable in a place that is not normally on your PATH,
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you may want to set up a symlink in ``/usr/local/bin``.
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On Windows, see `PCbuild/readme.txt
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<https://github.com/python/cpython/blob/master/PCbuild/readme.txt>`_.
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If you wish, you can create a subdirectory and invoke configure from there.
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For example::
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mkdir debug
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cd debug
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../configure --with-pydebug
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make
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make test
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(This will fail if you *also* built at the top-level directory. You should do
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a ``make clean`` at the toplevel first.)
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To get an optimized build of Python, ``configure --enable-optimizations``
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before you run ``make``. This sets the default make targets up to enable
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Profile Guided Optimization (PGO) and may be used to auto-enable Link Time
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Optimization (LTO) on some platforms. For more details, see the sections
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below.
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Profile Guided Optimization
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^^^^^^^^^^^^^^^^^^^^^^^^^^^
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PGO takes advantage of recent versions of the GCC or Clang compilers. If used,
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either via ``configure --enable-optimizations`` or by manually running
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``make profile-opt`` regardless of configure flags, the optimized build
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process will perform the following steps:
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The entire Python directory is cleaned of temporary files that may have
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resulted from a previous compilation.
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An instrumented version of the interpreter is built, using suitable compiler
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flags for each flavour. Note that this is just an intermediary step. The
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binary resulting from this step is not good for real life workloads as it has
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profiling instructions embedded inside.
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After the instrumented interpreter is built, the Makefile will run a training
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workload. This is necessary in order to profile the interpreter execution.
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Note also that any output, both stdout and stderr, that may appear at this step
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is suppressed.
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The final step is to build the actual interpreter, using the information
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collected from the instrumented one. The end result will be a Python binary
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that is optimized; suitable for distribution or production installation.
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Link Time Optimization
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^^^^^^^^^^^^^^^^^^^^^^
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Enabled via configure's ``--with-lto`` flag. LTO takes advantage of the
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ability of recent compiler toolchains to optimize across the otherwise
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arbitrary ``.o`` file boundary when building final executables or shared
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libraries for additional performance gains.
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What's New
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----------
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We have a comprehensive overview of the changes in the `What's New in Python
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3.8 <https://docs.python.org/3.8/whatsnew/3.8.html>`_ document. For a more
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detailed change log, read `Misc/NEWS
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<https://github.com/python/cpython/blob/master/Misc/NEWS.d>`_, but a full
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accounting of changes can only be gleaned from the `commit history
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<https://github.com/python/cpython/commits/master>`_.
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If you want to install multiple versions of Python see the section below
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entitled "Installing multiple versions".
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Documentation
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-------------
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`Documentation for Python 3.8 <https://docs.python.org/3.8/>`_ is online,
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updated daily.
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It can also be downloaded in many formats for faster access. The documentation
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is downloadable in HTML, PDF, and reStructuredText formats; the latter version
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is primarily for documentation authors, translators, and people with special
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formatting requirements.
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For information about building Python's documentation, refer to `Doc/README.rst
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<https://github.com/python/cpython/blob/master/Doc/README.rst>`_.
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Converting From Python 2.x to 3.x
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---------------------------------
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Significant backward incompatible changes were made for the release of Python
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3.0, which may cause programs written for Python 2 to fail when run with Python
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3. For more information about porting your code from Python 2 to Python 3, see
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the `Porting HOWTO <https://docs.python.org/3/howto/pyporting.html>`_.
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Testing
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-------
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To test the interpreter, type ``make test`` in the top-level directory. The
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test set produces some output. You can generally ignore the messages about
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skipped tests due to optional features which can't be imported. If a message
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is printed about a failed test or a traceback or core dump is produced,
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something is wrong.
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By default, tests are prevented from overusing resources like disk space and
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memory. To enable these tests, run ``make testall``.
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If any tests fail, you can re-run the failing test(s) in verbose mode. For
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example, if ``test_os`` and ``test_gdb`` failed, you can run::
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make test TESTOPTS="-v test_os test_gdb"
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If the failure persists and appears to be a problem with Python rather than
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your environment, you can `file a bug report <https://bugs.python.org>`_ and
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include relevant output from that command to show the issue.
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See `Running & Writing Tests <https://devguide.python.org/runtests/>`_
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for more on running tests.
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Installing multiple versions
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----------------------------
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On Unix and Mac systems if you intend to install multiple versions of Python
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using the same installation prefix (``--prefix`` argument to the configure
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script) you must take care that your primary python executable is not
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overwritten by the installation of a different version. All files and
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directories installed using ``make altinstall`` contain the major and minor
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version and can thus live side-by-side. ``make install`` also creates
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``${prefix}/bin/python3`` which refers to ``${prefix}/bin/pythonX.Y``. If you
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intend to install multiple versions using the same prefix you must decide which
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version (if any) is your "primary" version. Install that version using ``make
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install``. Install all other versions using ``make altinstall``.
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For example, if you want to install Python 2.7, 3.6, and 3.8 with 3.8 being the
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primary version, you would execute ``make install`` in your 3.8 build directory
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and ``make altinstall`` in the others.
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Issue Tracker and Mailing List
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------------------------------
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Bug reports are welcome! You can use the `issue tracker
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<https://bugs.python.org>`_ to report bugs, and/or submit pull requests `on
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GitHub <https://github.com/python/cpython>`_.
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You can also follow development discussion on the `python-dev mailing list
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<https://mail.python.org/mailman/listinfo/python-dev/>`_.
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Proposals for enhancement
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-------------------------
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If you have a proposal to change Python, you may want to send an email to the
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comp.lang.python or `python-ideas`_ mailing lists for initial feedback. A
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Python Enhancement Proposal (PEP) may be submitted if your idea gains ground.
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All current PEPs, as well as guidelines for submitting a new PEP, are listed at
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`python.org/dev/peps/ <https://www.python.org/dev/peps/>`_.
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.. _python-ideas: https://mail.python.org/mailman/listinfo/python-ideas/
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Release Schedule
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----------------
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See :pep:`569` for Python 3.8 release details.
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Copyright and License Information
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---------------------------------
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Copyright (c) 2001-2019 Python Software Foundation. All rights reserved.
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Copyright (c) 2000 BeOpen.com. All rights reserved.
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Copyright (c) 1995-2001 Corporation for National Research Initiatives. All
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rights reserved.
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Copyright (c) 1991-1995 Stichting Mathematisch Centrum. All rights reserved.
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See the file "LICENSE" for information on the history of this software, terms &
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conditions for usage, and a DISCLAIMER OF ALL WARRANTIES.
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This Python distribution contains *no* GNU General Public License (GPL) code,
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so it may be used in proprietary projects. There are interfaces to some GNU
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code but these are entirely optional.
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All trademarks referenced herein are property of their respective holders.
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