<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def stop(cls):
 """ Stops location updates if currently updating. """

        manager = LocationManager.instance()
        if manager:
            for l in manager.listeners:
                manager.removeUpdates(l)
            manager.listeners = []