general general remarks changes although the python line covered in the two most recent editions of this book is largely the same language as its predecessorit differs in some crucial ways as discussed in the preface and summarized in the preceding section ' nonoptional unicode modelmandatory new-style classesand broader emphasis on generators and other functional tools alone can make it materially different experience on the wholepython may be cleaner languagebut it is also in many ways more sophisticated languagerelying upon concepts that are substantially more advanced in factsome of its changes seem to assume you must already know python in order to learn python the preface mentioned some of the more prominent circular knowledge dependencies in that imply forward topic dependencies as random examplethe rationale for wrapping dictionary views in list call in is incredibly subtle and requires substantial foreknowledge--of viewsgeneratorsand the iteration protocolat the least keyword arguments are similarly required in simple tools ( printingstring formattingdictionary creationand sortingthat crop up long before newcomer learns enough about functions to understand them fully one of this book' goals is to help bridge this knowledge gap in today' / dual-version world changes in libraries and tools there are additional changes in python not listed in this appendixsimply because they don' affect this book for examplesome standard libraries and development tools are outside this book' core language scopethough some are mentioned along the way ( timeit)and others have always been covered here ( pydocfor completenessthe following sections note developments in these categories some of the changes in these categories are also listed later in this appendixin conjunction with the book edition and python version in which they were introduced standard library changes formally speakingthe python standard library is not part of this book' core language subjecteven though it' always available with pythonand permeates realistic python programs in factthe libraries were not subject to the temporary language changes moratorium enacted during ' development because of thischanges in the standard library have larger impact on applicationsfocused books like programming python than they do here although most standard appendix cpython changes and this book