Return the current time, as a float number of seconds since the epoch.
If SPECIFIED-TIME is given, it is the time to convert to float
instead of the current time. The argument should have the form
(HIGH LOW) or (HIGH LOW USEC) or (HIGH LOW USEC PSEC). Thus,
you can use times from `current-time' and from `file-attributes'.
SPECIFIED-TIME can also have the form (HIGH . LOW), but this is
considered obsolete.
WARNING: Since the result is floating point, it may not be exact.
If precise time stamps are required, use either `current-time',
or (if you need time as a string) `format-time-string'.
(fn &optional SPECIFIED-TIME)