This module implements the interface to NIST's secure hash
algorithm, known as SHA-1. SHA-1 is an improved version of the
original SHA hash algorithm. It is used in the same way as the
md5 module: use new() to create an sha object, then feed this
object with arbitrary strings using the update() method, and at
any point you can ask it for the digest of the concatenation of
the strings fed to it so far. SHA-1 digests are 160 bits instead
of MD5's 128 bits. The following values are provided as
constants in the module and as attributes of the sha objects
returned by new(): 1. This size is used to allow an arbitrary
string to be hashed. An sha object has the same methods as md5
objects: m.update(a); m.update(b)is equivalent to See About this
document... for information on suggesting changes.