def increment!(amount = 1, time: Time.now)
      if !increment(amount, time: time)
        raise TrafficJam::LimitExceededError.new(self)
      end
    end
def increment!(amount = 1, time: Time.now)
      if !increment(amount, time: time)
        raise TrafficJam::LimitExceededError.new(self)
      end
    end
Increment the amount used by the given number. Does not perform increment
 if the operation would exceed the limit. Raises an exception if the
 operation is unsuccessful. Time of# increment can be specified optionally
 with a keyword argument, which is useful for rolling back with a
 decrement.

 @param amount [Integer] amount to increment by
 @param time [Time] time when increment occurs
 @return [nil]
 @raise [TrafficJam::LimitExceededError] if incrementing would exceed the
   limit