Copyright (c) 2008-2011 The pip developers (see AUTHORS.txt file)

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
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permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.