This is just a wrapper for perl's 'crypt()', which can do everything you
would probably want to do to store a password, but this is to make usage
easier.

The object stringifies to the return string of the crypt() function, which
is usually (see the KNOWN ISSUES manpage) in Modular Crypt Format:

# scalar($hashed):
# v digest v hash ->
# $5$%RK2BU%L$aFZd1/4Gpko/sJZ8Oh.ZHg9UvxCjkH1YYoLZI6tw7K8
# ^ salt ^

That you can store, etc, retrieve then give it to 'password()' again to
'->check($given_password)' or string compare to the output of a new
'password($given_password)'.

If the given string is already hashed it is assumed to be okay to use it as
is. This means users can supply pre-hashed passwords to you.