appendix python coding conventions that are incompatible needless to saysomeone is not going to have positive learning experience if everything appears to be broken even the official documentation is not entirely up-to-date with python coding requirementswhile writing this bookthe author submitted numerous bug reports concerning documentation errors and omissions finallyeven though python is described as the latest and greatestit suffers from numerous performance and behavioral problems for examplethe / system in the initial release exhibits truly horrific and unacceptable runtime performance the separation of bytes and unicode is also not without problem even some of the built-in library modules are broken due to changes related to / and string handling obviously these issues will improve with time as more programmers stress-test the release howeverin the opinion of this authorpython is really only suitable for experimental use by seasoned python veterans if you're looking for stability and production quality codestick with python until some of the kinks have had time to be worked out of the python series new language features this section outlines some features of python that are not supported in python source code encoding and identifiers python assumes that source code is encoded as utf- in additionthe rules on what characters are legal in an identifier have been relaxed specificallyidentifiers can contain any valid unicode character with code point of + or greater for examplep print( * *rjust because you can use such characters in your source code doesn' mean that it' good idea not all editorsterminalsor development tools are equally adept at unicode handling plusit is extremely annoying to force programmers to type awkward key sequences for characters not visibly present on standard keyboard (not to mention the fact that it might make some of the gray-bearded hackers in the office tell everyone another amusing apl storysoit' probably better to reserve the use of unicode characters for comments and string literals set literals set of items can now be defined by enclosing collection of values in braces items for exampledays 'mon''tue''wed''thu''fri''sat''sunthis syntax is the same as using the set(functiondays set(['mon''tue''wed''thu''fri''sat''sun'] lib fl ff