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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 execute(self):
 """ Executes ``ansible-playbook`` and returns a string. :return: str """

        if self._ansible_command is None:
            self.bake()

        try:
            self._config.driver.sanity_checks()
            cmd = util.run_command(
                self._ansible_command, debug=self._config.debug)
            return cmd.stdout.decode('utf-8')
        except sh.ErrorReturnCode as e:
            out = e.stdout.decode('utf-8')
            util.sysexit_with_message(str(out), e.exit_code)