License
-------

Copyright (c) 2013-2018, Kim Davies. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

#. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

#. Redistributions in binary form must reproduce the above
   copyright notice, this list of conditions and the following
   disclaimer in the documentation and/or other materials provided with
   the distribution.

#. Neither the name of the copyright holder nor the names of the 
   contributors may be used to endorse or promote products derived 
   from this software without specific prior written permission.

#. THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS "AS IS" AND ANY
   EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR 
   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
   USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
   DAMAGE.

Portions of the codec implementation and unit tests are derived from the
Python standard library, which carries the `Python Software Foundation
License <https://docs.python.org/2/license.html>`_:

   Copyright (c) 2001-2014 Python Software Foundation; All Rights Reserved

Portions of the unit tests are derived from the Unicode standard, which 
is subject to the Unicode, Inc. License Agreement:

   Copyright (c) 1991-2014 Unicode, Inc. All rights reserved.
   Distributed under the Terms of Use in 
   <http://www.unicode.org/copyright.html>.

   Permission is hereby granted, free of charge, to any person obtaining
   a copy of the Unicode data files and any associated documentation
   (the "Data Files") or Unicode software and any associated documentation
   (the "Software") to deal in the Data Files or Software
   without restriction, including without limitation the rights to use,
   copy, modify, merge, publish, distribute, and/or sell copies of
   the Data Files or Software, and to permit persons to whom the Data Files
   or Software are furnished to do so, provided that
   
   (a) this copyright and permission notice appear with all copies 
   of the Data Files or Software,

   (b) this copyright and permission notice appear in associated 
   documentation, and

   (c) there is clear notice in each modified Data File or in the Software
   as well as in the documentation associated with the Data File(s) or
   Software that the data or software has been modified.

   THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF
   ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
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   NONINFRINGEMENT OF THIRD PARTY RIGHTS.
   IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS
   NOTICE BE LIABLE FOR ANY CLAIM, OR 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
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   Except as contained in this notice, the name of a copyright holder
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