Set the input data of the model

        :param X: input observations
        :type X: np.ndarray

def set_X(self, X):
        """
        Set the input data of the model

        :param X: input observations
        :type X: np.ndarray
        """
        assert isinstance(X, np.ndarray)
        state = self.update_model()
        self.update_model(False)
        self.X = ObsAr(X)
        self.update_model(state)