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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 message_handlers(self):
 """Iterate over the message handlers of the class."""

        index = lib.EnvGetNextDefmessageHandler(self._env, self._cls, 0)

        while index != 0:
            yield MessageHandler(self._env, self._cls, index)

            index = lib.EnvGetNextDefmessageHandler(self._env, self._cls, index)