Each chapter describes one of the main sub-packages of the fipy package. The sub-package fipy.package can be found in the directory fipy/package/. In a few cases, there will be packages within packages, e.g. fipy.package.subpackage located in fipy/package/subpackage/. These sub-sub-packages will not be given their own chapters; rather, their contents will be described in the chapter for their containing package.