Sets this's max age to max_age.
If max_age is -1, the cookie is a session cookie, and will expire at the end of the client's session. Otherwise, it is the
number of seconds until the cookie expires. You can use the constants
COOKIE_MAX_AGE_ONE_HOUR, COOKIE_MAX_AGE_ONE_DAY,
COOKIE_MAX_AGE_ONE_WEEK and
COOKIE_MAX_AGE_ONE_YEAR (or multiples thereof) to calculate this value.
(A value of 0 indicates that the cookie should be considered already-expired.)
(This sets the same property as set_expires.)
| this |
a Cookie |
| max_age |
the new max age |