Get the current lap start time.
Return the duration of time since the last call to lap (or start).
Change the lap start time.
Check the current lap time without starting a new lap.
Set a custom value for the lap start time.
Start the next lap. This will get the current time and set it so that the next call to lap will take the difference between the new time with the time this was called.
Used to track "laps" of time, where each call to lap will return the time since the last call to lap.