Create a new HMAC object.
key: key for the keyed hash object.
msg: Initial input for the hash, if provided.
digestmod: A module supporting PEP 247. Defaults to the md5 module.
copy(self)
Return a separate copy of this hashing object.
An update to this copy won't affect the original object.
digest(self)
Return the hash value of this hashing object.
This returns a string containing 8-bit data. The object is
not altered in any way by this function; you can continue
updating the object after calling this function.