Python 3.9.0b4 released, Python 3.9 is still in development, this version 3.9.0b4 is the fourth of five planned beta version previews.

Beta version previews are intended to provide the community at large with an opportunity to test new features and bug fixes and prepare their projects to support new feature releases.

· Some of the main new features and changes in Python 3.9:

· PEP 584, add Union operator to built-in dict function

· PEP 585, Generic types built into type annotations

· PEP 593, Flexible function and variable annotations

· PEP 602, Python adopts a stable annual release cadence

· PEP 615, support for the IANA time zone database in the standard library

· PEP 616, String methods for removing prefixes and suffixes

· PEP 617, a new PEG parser for CPython

· BPO 38379, garbage collection does not block resurrected objects

· BPO 38692, add os.pidfd_open for process management without race and signal

· BPO 39926, Unicode support upgraded to 13.0.0

· BPO 1635741, Python no longer leaks memory when it is initialized multiple times in the same process

· Some Python built-in functions (range, tuple, set, frozenset, list, dict) are now faster using PEP 590 vectorcall

· Some Python modules (_abc, audioop, _bz2, _codecs, _contextvars, _crypt, _functools, _json, _locale, operator, resource, time, _weakref) now use polyphase initialization defined by PEP 489

· Some standard library modules (audioop, ast, grp, _hashlib, pwd, _posixsubprocess, random, select, struct, termios, zlib) now use the stable ABI defined by PEP 384