'reilly networksee the 'reilly website atconventions used in this book the following font conventions are used in this bookitalic used for file and directory namesto emphasize new terms when first introducedand for some comments within code sections constant width used for code listings and to designate modulesmethodsoptionsclassesfunctionsstatementsprogramsobjectsand html tags constant width bold used in code sections to show user input constant width italic used to mark replaceables this icon designates note related to the nearby text this icon designates warning related to the nearby text acknowledgments acknowledged numerous people in the preface of learning pythonfourth editionless than year agobecause that book is precursor to this oneand because the set is largely the samei won' repeat the list in its entirety here in shortthoughi' grateful too'reillyfor promoting pythonand publishing "meatybooks in the open source domain the python communitywhich has occupied sizeable portions of my world since the thousands of students who attended the python classes 've taught since preface xxxvii