The first time that a user clocks in each day, this function will be
called to determine what the length of the current workday is. If
the return value is nil, or equal to `timeclock-workday', nothing special
-will be done. If it is a quantity different from `timeclock-workday',
+will be done. If it is a quantity different from `timeclock-workday',
however, a record will be output to the timelog file to note the fact that
that day has a different length from the norm."
:type '(choice (const nil) function)