presented in this book--importing features from __future__avoiding versionspecific toolsand so on many of the examples in this book are platform-neutral for examplessee the benchmarking tools in the module reloaders and comma formatter in the class tree listers in most of the larger decorator examples in and the joke script at the end of and more as long as you understand / core language differencescoding around them is often straightforward if you're interested in writing code for both and xsee also six-- library of crossversion mapping and renaming toolswhich currently lives at org/six naturallythis package can' offset every difference in language semantics and library apisand in many cases you must use its library tools instead of straight python to realize its portability gains in exchangethoughyour programs become much more version-neutral when using this library' tools fifth edition python changes the following specific changes were made in the python and lines after the fourth edition was publishedand have been incorporated into this edition specificallythis section documents python book-related changes in pythons and changes in python on the technical frontpython mostly incorporates as back-ports handful of features that were covered in the prior edition of this bookbut formerly as -only features this new fifth edition presents these as tools as well among theseset literals{ set and dictionary comprehensions{ for in 'spam'}{cc for in 'spam'dictionary viewsincorporated as optional methodsdict viewkeys()dict viewvalues()dict viewitems(comma separators and field autonumbering in str format (from )'{: {}format( 'spam'nested with statement context managers (from )with (as xy(as yfloat object repr display improvements (back-ported from see ahead appendix cpython changes and this book