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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 check(self, orb):
 """Method that check whether or not the listener is triggered Args: orb (Orbit):
 Return: bool: True if there is a zero-crossing for the parameter watched by the listener """


        return self.prev is not None and np.sign(self(orb)) != np.sign(self(self.prev))