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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 add_response(self, response, value):
 """ Add response to staircase. Parameters response : int or bool 0 or 1. value : int or float Signal corresponding to response. """

        if value != "stop":
            self.X = pd.concat([self.X, pd.DataFrame({"Signal":[value]})])
            self.y = np.array(list(self.y) + [response])
            if len(set(list(self.y))) > 1:
                self.model = self.fit_model(self.X , self.y)