(Disclosure: I'm one of the authors of BLAKE2.)

Please include BLAKE2 in hashlib. It well-suited for hashing long inputs (e.g. files), because it is substantially faster than SHA-3, SHA-2, SHA-1, or MD5 while also being safer than SHA-2, SHA-1, or MD5.

BLAKE2 and/or its relatives, BLAKE, ChaCha20, and Salsa20, have gotten extensive cryptographic peer review.

It is widely used in modern applications and widely supported in modern crypto libraries (https://en.wikipedia.org/wiki/BLAKE_%28hash_function%29#BLAKE2_uses).

Here is the official reference implementation: https://github.com/BLAKE2

Here are some Python modules (wrappers or implementations):
 * https://github.com/buggywhip/blake2_py
 * https://github.com/dchest/pyblake2
 * https://github.com/darjeeling/python-blake2