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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 _update(self):
 """Update the current model using one round of Gibbs sampling. """

        initial_time = time.time()

        self._updateHiddenStateTrajectories()
        self._updateEmissionProbabilities()
        self._updateTransitionMatrix()

        final_time = time.time()
        elapsed_time = final_time - initial_time
        logger().info("BHMM update iteration took %.3f s" % elapsed_time)