the book examples package described earlier also includes portable example demo launcher scripts named pydemos and pygadgetswhich provide quick look at some of this book' major guiand web-based examples these scripts and their launcherslocated at the top of the examples treecan be run to self-configure program and module search pathsand so can generally be run immediately on compatible platformsincluding windows see the package' readme files as well as the overviews near the end of and for more on these scripts code reuse policies we now interrupt this preface for word from the legal department this book is here to help you get your job done in generalyou may use the code in this book in your programs and documentation you do not need to contact us for permission unless you're reproducing significant portion of the code for examplewriting program that uses several chunks of code from this book does not require permission selling or distributing cd-rom of examples from 'reilly books does require permission answering question by citing this book and quoting example code does not require permission incorporating significant amount of example code from this book into your product' documentation does require permission we appreciatebut do not requireattribution an attribution usually includes the titleauthorpublisherand isbn for example"programming pythonfourth editionby mark lutz ( 'reillycopyright mark lutz- - contacting 'reilly described my own examples and updates sites in the prior section in addition to that adviceyou can also address comments and questions about this book to the publishero'reilly mediainc gravenstein highway north sebastopolca (in the united states and canada(international/local(faxas mentionedo'reilly maintains web page for this bookwhich lists errataexamplesand any additional information you can access this page atto comment or ask technical questions about this booksend email tobookquestions@oreilly com xxxvi preface