From python official website I found this :
Python 3.4.0 alpha 2 was released on September 9th, 2013. This is a preview release of the next major release of Python, Python 3.4, and is not suitable for production environments.
Major new features of the 3.4 series, compared to 3.3
Python 3.4 includes a range of improvements of the 3.x series, including hundreds of small improvements and bug fixes. Major new features and changes in the 3.4 release series so far include:
PEP 435, a standardized "enum" module
PEP 442, improved semantics for object finalization
PEP 443, adding single-dispatch generic functions to the standard library
PEP 445, a new C API for implementing custom memory allocators
PEP 446, changing file descriptors to not be inherited by default in subprocesses...
