typing-extensions
A. HISTORY OF  THE SOFTWARE
  ==========================
  
  Python was  created in the early 1990s by Guido van Rossum at Stichting
  Mathematisch  Centrum (CWI, see http://www.cwi.nl) in the Netherlands
  as a  successor of a language called ABC.   Guido remains Python's
  principal  author, although it includes many contributions from others.
  
  In 1995,  Guido continued his work on Python at the Corporation for
  National  Research Initiatives (CNRI, see http://www.cnri.reston.va.us)
  in Reston,  Virginia where he released several versions of the
  software.
  
  In May 2000,  Guido and the Python core development team moved to
  BeOpen.com to  form the BeOpen PythonLabs team.  In  October of the same
  year, the  PythonLabs team moved to Digital Creations (now Zope
  Corporation,  see http://www.zope.com).  In 2001, the  Python Software
  Foundation  (PSF, see http://www.python.org/psf/) was formed, a
  non-profit  organization created specifically to own Python-related
  Intellectual  Property.  Zope Corporation is a  sponsoring member of
  the PSF.
  
  All Python  releases are Open Source (see http://www.opensource.org for
  the Open  Source Definition).  Historically, most,  but not all, Python
  releases have  also been GPL-compatible; the table below summarizes
  the various  releases.
  
  Release       Derived  Year        Owner         GPL-
  from                               compatible? (1)
  
  0.9.0 thru 1.2              1991-1995   CWI                 yes
  1.3 thru 1.5.2  1.2                  1995-1999   CNRI         yes
  1.6            1.5.2     2000                  CNRI                 no
  2.0            1.6      2000                  BeOpen.com  no
  1.6.1          1.6      2001                  CNRI                 yes  (2)
  2.1            2.0+1.6.1   2001         PSF      no
  2.0.1          2.0+1.6.1   2001         PSF      yes
  2.1.1          2.1+2.0.1   2001         PSF      yes
  2.1.2          2.1.1     2002                  PSF                  yes
  2.1.3                   2.1.2        2002     PSF                  yes
  2.2 and above   2.1.1               2001-now              PSF         yes
  
  Footnotes:
  
  (1)  GPL-compatible doesn't mean that we're distributing Python under
  the GPL.   All Python licenses, unlike the GPL, let you distribute
  a modified version without making your  changes open source.  The
  GPL-compatible licenses make it possible to  combine Python with
  other software that is released under the  GPL; the others don't.
  
  (2) According  to Richard Stallman, 1.6.1 is not GPL-compatible,
  because its license has a choice of law  clause.  According to
  CNRI, however, Stallman's lawyer has told  CNRI's lawyer that 1.6.1
  is "not incompatible" with the  GPL.
  
  Thanks to the  many outside volunteers who have worked under Guido's
  direction to  make these releases possible.
  
  
  B. TERMS AND  CONDITIONS FOR ACCESSING OR OTHERWISE USING PYTHON
  ===============================================================
  
  PYTHON  SOFTWARE FOUNDATION LICENSE VERSION 2
  --------------------------------------------
  
  1. This  LICENSE AGREEMENT is between the Python Software Foundation
  ("PSF"),  and the Individual or Organization ("Licensee") accessing and
  otherwise  using this software ("Python") in source or binary form and
  its  associated documentation.
  
  2. Subject to  the terms and conditions of this License Agreement, PSF hereby
  grants  Licensee a nonexclusive, royalty-free, world-wide license to reproduce,
  analyze,  test, perform and/or display publicly, prepare derivative works,
  distribute,  and otherwise use Python alone or in any derivative version,
  provided,  however, that PSF's License Agreement and PSF's notice of copyright,
  i.e.,  "Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
  2011, 2012,  2013, 2014 Python Software Foundation; All Rights Reserved" are
  retained in  Python alone or in any derivative version prepared by Licensee.
  
  3. In the  event Licensee prepares a derivative work that is based on
  or  incorporates Python or any part thereof, and wants to make
  the  derivative work available to others as provided herein, then
  Licensee  hereby agrees to include in any such work a brief summary of
  the changes  made to Python.
  
  4. PSF is  making Python available to Licensee on an "AS IS"
  basis.  PSF MAKES NO REPRESENTATIONS OR WARRANTIES,  EXPRESS OR
  IMPLIED.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF  MAKES NO AND
  DISCLAIMS ANY  REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
  FOR ANY  PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT
  INFRINGE ANY  THIRD PARTY RIGHTS.
  
  5. PSF SHALL  NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
  FOR ANY  INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
  A RESULT OF  MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON,
  OR ANY  DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
  
  6. This  License Agreement will automatically terminate upon a material
  breach of its  terms and conditions.
  
  7. Nothing in  this License Agreement shall be deemed to create any
  relationship  of agency, partnership, or joint venture between PSF and
  Licensee.  This License Agreement does not grant  permission to use PSF
  trademarks or  trade name in a trademark sense to endorse or promote
  products or  services of Licensee, or any third party.
  
  8. By  copying, installing or otherwise using Python, Licensee
  agrees to be  bound by the terms and conditions of this License
  Agreement.
  
  
  BEOPEN.COM  LICENSE AGREEMENT FOR PYTHON 2.0
  -------------------------------------------
  
  BEOPEN PYTHON  OPEN SOURCE LICENSE AGREEMENT VERSION 1
  
  1. This  LICENSE AGREEMENT is between BeOpen.com ("BeOpen"), having an
  office at 160  Saratoga Avenue, Santa Clara, CA 95051, and the
  Individual or  Organization ("Licensee") accessing and otherwise using
  this software  in source or binary form and its associated
  documentation  ("the Software").
  
  2. Subject to  the terms and conditions of this BeOpen Python License
  Agreement,  BeOpen hereby grants Licensee a non-exclusive,
  royalty-free,  world-wide license to reproduce, analyze, test, perform
  and/or  display publicly, prepare derivative works, distribute, and
  otherwise use  the Software alone or in any derivative version,
  provided,  however, that the BeOpen Python License is retained in the
  Software,  alone or in any derivative version prepared by Licensee.
  
  3. BeOpen is  making the Software available to Licensee on an "AS IS"
  basis.  BEOPEN MAKES NO REPRESENTATIONS OR  WARRANTIES, EXPRESS OR
  IMPLIED.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, BEOPEN  MAKES NO AND
  DISCLAIMS ANY  REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
  FOR ANY  PARTICULAR PURPOSE OR THAT THE USE OF THE SOFTWARE WILL NOT
  INFRINGE ANY  THIRD PARTY RIGHTS.
  
  4. BEOPEN SHALL  NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF THE
  SOFTWARE FOR  ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS
  AS A RESULT  OF USING, MODIFYING OR DISTRIBUTING THE SOFTWARE, OR ANY
  DERIVATIVE  THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
  
  5. This  License Agreement will automatically terminate upon a material
  breach of its  terms and conditions.
  
  6. This  License Agreement shall be governed by and interpreted in all
  respects by  the law of the State of California, excluding conflict of
  law  provisions.  Nothing in this License  Agreement shall be deemed to
  create any  relationship of agency, partnership, or joint venture
  between  BeOpen and Licensee.  This License  Agreement does not grant
  permission to  use BeOpen trademarks or trade names in a trademark
  sense to  endorse or promote products or services of Licensee, or any
  third  party.  As an exception, the "BeOpen  Python" logos available at
  http://www.pythonlabs.com/logos.html  may be used according to the
  permissions  granted on that web page.
  
  7. By  copying, installing or otherwise using the software, Licensee
  agrees to be  bound by the terms and conditions of this License
  Agreement.
  
  
  CNRI LICENSE  AGREEMENT FOR PYTHON 1.6.1
  ---------------------------------------
  
  1. This LICENSE  AGREEMENT is between the Corporation for National
  Research  Initiatives, having an office at 1895 Preston White Drive,
  Reston, VA  20191 ("CNRI"), and the Individual or Organization
  ("Licensee")  accessing and otherwise using Python 1.6.1 software in
  source or  binary form and its associated documentation.
  
  2. Subject to  the terms and conditions of this License Agreement, CNRI
  hereby grants  Licensee a nonexclusive, royalty-free, world-wide
  license to  reproduce, analyze, test, perform and/or display publicly,
  prepare  derivative works, distribute, and otherwise use Python 1.6.1
  alone or in  any derivative version, provided, however, that CNRI's
  License  Agreement and CNRI's notice of copyright, i.e., "Copyright (c)
  1995-2001  Corporation for National Research Initiatives; All Rights
  Reserved"  are retained in Python 1.6.1 alone or in any derivative
  version  prepared by Licensee.  Alternately, in  lieu of CNRI's License
  Agreement,  Licensee may substitute the following text (omitting the
  quotes):  "Python 1.6.1 is made available subject to the terms and
  conditions in  CNRI's License Agreement.  This Agreement  together with
  Python 1.6.1  may be located on the Internet using the following
  unique,  persistent identifier (known as a handle): 1895.22/1013.  This
  Agreement may  also be obtained from a proxy server on the Internet
  using the  following URL: http://hdl.handle.net/1895.22/1013".
  
  3. In the  event Licensee prepares a derivative work that is based on
  or  incorporates Python 1.6.1 or any part thereof, and wants to make
  the  derivative work available to others as provided herein, then
  Licensee  hereby agrees to include in any such work a brief summary of
  the changes  made to Python 1.6.1.
  
  4. CNRI is  making Python 1.6.1 available to Licensee on an "AS IS"
  basis.  CNRI MAKES NO REPRESENTATIONS OR WARRANTIES,  EXPRESS OR
  IMPLIED.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, CNRI  MAKES NO AND
  DISCLAIMS ANY  REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
  FOR ANY  PARTICULAR PURPOSE OR THAT THE USE OF PYTHON 1.6.1 WILL NOT
  INFRINGE ANY  THIRD PARTY RIGHTS.
  
  5. CNRI SHALL  NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
  1.6.1 FOR ANY  INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
  A RESULT OF  MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON 1.6.1,
  OR ANY DERIVATIVE  THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
  
  6. This  License Agreement will automatically terminate upon a material
  breach of its  terms and conditions.
  
  7. This  License Agreement shall be governed by the federal
  intellectual  property law of the United States, including without
  limitation  the federal copyright law, and, to the extent such
  U.S. federal  law does not apply, by the law of the Commonwealth of
  Virginia,  excluding Virginia's conflict of law provisions.
  Notwithstanding  the foregoing, with regard to derivative works based
  on Python  1.6.1 that incorporate non-separable material that was
  previously  distributed under the GNU General Public License (GPL), the
  law of the  Commonwealth of Virginia shall govern this License
  Agreement  only as to issues arising under or with respect to
  Paragraphs 4,  5, and 7 of this License Agreement.   Nothing in this
  License  Agreement shall be deemed to create any relationship of
  agency,  partnership, or joint venture between CNRI and Licensee.  This
  License Agreement  does not grant permission to use CNRI trademarks or
  trade name in  a trademark sense to endorse or promote products or
  services of  Licensee, or any third party.
  
  8. By  clicking on the "ACCEPT" button where indicated, or by copying,
  installing or  otherwise using Python 1.6.1, Licensee agrees to be
  bound by the  terms and conditions of this License Agreement.
  
  ACCEPT
  
  
  CWI LICENSE  AGREEMENT FOR PYTHON 0.9.0 THROUGH 1.2
  --------------------------------------------------
  
  Copyright (c)  1991 - 1995, Stichting Mathematisch Centrum Amsterdam,
  The  Netherlands.  All rights reserved.
  
  Permission to  use, copy, modify, and distribute this software and its
  documentation  for any purpose and without fee is hereby granted,
  provided that  the above copyright notice appear in all copies and that
  both that  copyright notice and this permission notice appear in
  supporting  documentation, and that the name of Stichting Mathematisch
  Centrum or  CWI not be used in advertising or publicity pertaining to
  distribution  of the software without specific, written prior
  permission.
  
  STICHTING  MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO
  THIS  SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
  FITNESS, IN  NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLE
  FOR ANY  SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER  RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  OF OR IN CONNECTION  WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
