See Source File
Tango Dual License: 3-Clause BSD License / Academic Free License v3.0. See LICENSE_TANGO.txt for details.
Copyright (c) 2005 John Chapman. Some parts copyright (c) 2009-2016 dunnhumby Germany GmbH. All rights reserved.
Mid 2005: Initial release Apr 2007: reshaped
John Chapman, Kris