def define_rate(name, description, unit_seconds=1, manager=counters):
 counter = _RateCounter(name, description, unit_seconds)
 manager.register(counter)
 return counter

def define_rate ( name , description , unit_seconds = 1 , manager = counters ) : counter = _RateCounter ( name , description , unit_seconds ) manager . register ( counter ) return counter
creates a performance counter which tracks some rate at which a value accumulates over the course of the program .