Returns the Unix timestamp value corresponding to the
parameters, which are supplied in the order
(optionally) whether the value is in Daylight Savings Time. This
timestamp is the number of seconds elapsed between the Unix epoch and
the given date and time.
The order of the parameters is different from that of the
mktime() call, to
make it simpler to leave out unneeded arguments. Any arguments left
out are given the current local date and time.