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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 rotation_matrix(self):
 """Get the 3x3 rotation matrix equivalent of the quaternion rotation. Returns: A 3x3 orthogonal rotation matrix as a 3x3 Numpy array Note: This feature only makes sense when referring to a unit quaternion. Calling this method will implicitly normalise the Quaternion object to a unit quaternion if it is not already one. """

        self._normalise()
        product_matrix = np.dot(self._q_matrix(), self._q_bar_matrix().conj().transpose())
        return product_matrix[1:][:,1:]