Models an OS-specific file-system.
Tango Dual License: 3-Clause BSD License / Academic Free License v3.0. See LICENSE_TANGO.txt for details.
Copyright (c) 2004 Kris Bell. Some parts copyright (c) 2009-2016 dunnhumby Germany GmbH. All rights reserved.
Mar 2004: Initial release Feb 2007: Now using mutating paths