Python 3, PEP 247 compliant, multihash implementation.

From the multihash spec, this implementation is PEP247 (update(arg), digest(), hexdigest(), and copy()) compliant:

>>> import multihash
>>> m = multihash.sha1()
>>> m.update('foo'.encode())
>>> print(m.hexdigest())
11140beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33