his book is intended to be concise reference to the python programming language although an experienced programmer will probably be able to learn python from this bookit' not intended to be an extended tutorial or treatise on how to program ratherthe goal is to present the core python languageand the most essential parts of the python library in manner that' accurate and concise this book assumes that the reader has prior programming experience with python or another language such as or java in additiona general familiarity with systems programming topics (for examplebasic operating system concepts and network programmingmay be useful in understanding certain parts of the library reference python is freely available for download at additionthe python website includes links to documentationhow-to guidesand wide assortment of third-party software this edition of python essential reference comes at pivotal time in python' evolution python and python are being released almost simultaneously yetpython is release that breaks backwards compatibility with prior python versions as an author and programmeri' faced with dilemmado simply jump forward to python or do build upon the python releases that are more familiar to most programmersyears agoas programmer used to treat certain books as the ultimate authority on what programming language features should be used for exampleif you were using something that wasn' documented in the & bookit probably wasn' going to be portable and should be approached with caution this approach served me very well as programmer and it' the approach have decided to take in this edition of the essential reference namelyi have chosen to omit features of python that have been removed from python likewisei don' focus on features of python that have not been back-ported (although such features are still covered in an appendixas resulti hope this book can be useful companion for python programmersregardless of what python version is being used the fourth edition of python essential reference also includes some of the most exciting changes since its initial publication nearly ten years ago much of python' development throughout the last few years has focused on new programming language features--especially related to functional and meta programming as resultthe on functions and object-oriented programming have been greatly expanded to cover topics such as generatorsiteratorscoroutinesdecoratorsand metaclasses the library have been updated to focus on more modern modules examples and code fragments have also been updated throughout the book think most programmers will be quite pleased with the expanded coverage finallyit should be noted that python already includes thousands of pages of useful documentation the contents of this book are largely based on that documentationbut with number of key differences firstthis reference presents information in much more compact formwith different examples and alternative descriptions of many topics seconda significant number of topics in the library reference have been expanded lib fl ff