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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 _get_gradient_log_pdf(self):
 """ Method that finds gradient and its log at position """

        sub_vec = self.variable_assignments - self.model.mean.flatten()
        grad = - np.dot(self.model.precision_matrix, sub_vec)
        log_pdf = 0.5 * np.dot(sub_vec, grad)

        return grad, log_pdf