modulesgrouping them into packagesand changing api call patterns some library changes are much broaderthough python ' unicode modelfor examplecreates widespread differences in ' standard library--it potentially impacts any program that processes file contentfilenamesdirectory walkerspipesdescriptor filessocketstext in guisinternet protocols such as ftp and emailcgi scriptsweb content of many kindsand even some persistence tools such as dbm filesshelvesand pickles for more comprehensive list of changes in ' standard librariessee the "what' newdocuments for releases (especially in python' standard manual set because it uses python throughoutthe aforementioned programming python can also serve as guide to library changes tools changes though most development tools are the same between and ( for debuggingprofilingtimingand testing) few have undergone changes in along with the language and library among thesethe pydoc module documentation system has moved away from its former gui client model in and earlierreplacing it with an all web browser interface other noteworthy changes in this categorythe distutils packageused to distribute and install third-party softwareis to be subsumed by new packaging system in xthe new __pycache__ byte code storage scheme described in this bookthough an improvementpotentially impacts many python tools and programsand the internal implementation of threading changed as of to reduce contention by modifying the global interpreter lock (gilto use absolute time slices instead of virtual machine instruction counter migrating to if you are migrating from python to python xbe sure to also see the to automatic code conversion script that is shipped with python it' currently available in python' tools\scripts install folderor via web search this script cannot translate everythingand attempts to translate core language code primarily-- standard library apis may differ further stillit does reasonable job of converting much code to run under converselythe to back-conversion programcurrently available in the third-party domaincan also translate much python code to run in environments depending on your goals and constraintseither to or to may prove useful if you must maintain code for both python linessee the web for detailsand additional tools and techniques general remarks changes