It has been ten years since David Beazley wrote the first edition of Python Essential Reference. The book has proven itself as a valuable resource to Python developers and has been kept current over those ten years, with the fourth edition coming at an interesting time for Python. Python 3 was a major release that broke backwards compatibility. Python 3 has been around for a year now. That said, the current download page at the official Python site states, “If you don’t know which version to use, start with Python 2.6.4; more existing third party software is compatible with Python 2 than Python 3 right now.” Beazley in keeping with the pragmatic roots of a reference that sticks to what is ‘essential’ has removed the coverage on features from 2 that were removed from 3. At the same time, the primary focus for new features that came with 3 is limited to those that have been back-ported to 2. This approach, born out of a desire to keep the reference relevant, provides a blended approach that is above all else practical.

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