Execute the actions necessary to prepare the instances and returns
        None.

        :return: None

def execute(self):
        """
        Execute the actions necessary to prepare the instances and returns
        None.

        :return: None
        """
        self.print_info()

        if (self._config.state.prepared
                and not self._config.command_args.get('force')):
            msg = 'Skipping, instances already prepared.'
            LOG.warn(msg)
            return

        if not self._config.provisioner.playbooks.prepare:
            msg = 'Skipping, prepare playbook not configured.'
            LOG.warn(msg)
            return

        self._config.provisioner.prepare()
        self._config.state.change_state('prepared', True)