PyMOTW: os.path

Writing code to work with files on multiple platforms is easy using
the functions included in the os.path module. Even programs not
intended to be ported between platforms should use os.path to make
parsing path names reliable.

Read more: os.path

PyMOTW: hashlib

The hashlib module deprecates the separate md5 and sha
modules and makes their API consistent. To work with a specific hash
algorithm, use the appropriate constructor function to create a hash
object. Then you can use the same API to interact with the hash no
matter what algorithm is being used.

Read more at hashlib

PyMOTW: mmap

Use the mmap() function to create a memory-mapped file. There are
differences in the arguments and behaviors for mmap() between Unix
and Windows, which are not discussed below. For more details, refer to
the library documentation.

Read more at mmap