Return a new hmac object. If msg is present, the method call
update(msg) is made. digestmod is the digest
module for the HMAC object to use. It defaults to the
md5 module.
Update the hmac object with the string msg. Repeated calls
are equivalent to a single call with the concatenation of all the
arguments: m.update(a); m.update(b) is equivalent to
m.update(a + b).
Return the digest of the strings passed to the update()
method so far. This is a 16-byte string (for md5) or a
20-byte string (for sha) which may contain non-ASCII
characters, including NUL bytes.
Like digest() except the digest is returned as a string of
length 32 for md5 (40 for sha), containing
only hexadecimal digits. This may be used to exchange the value
safely in email or other non-binary environments.