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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def tick(self):
 """Mark the passage of time and decay the current rate accordingly."""

        instant_rate = self.count / float(self.tick_interval_s)
        self.count = 0
        if self.initialized:
            self.rate += (self.alpha * (instant_rate - self.rate))
        else:
            self.rate = instant_rate
            self.initialized = True