scandir, a better directory iterator and faster os.walk()
scandir() is a generator version of os.listdir() that returns
an iterator over files in a directory, and also exposes the
extra information most OSes provide while iterating files in a
directory (such as type and stat information).
This module also includes a version of os.walk() that uses
scandir() to speed it up significantly.
NOTE: If you're using Python version 3.5+, os.scandir() and the
speed improvements to os.walk() are already available in the
standard library.
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