Given the flow config and everything else, create a list of steps to run, sorted by step number.

        :return: List[StepSpec]

def _init_steps(self,):
        """
        Given the flow config and everything else, create a list of steps to run, sorted by step number.

        :return: List[StepSpec]
        """
        self._check_old_yaml_format()
        config_steps = self.flow_config.steps
        self._check_infinite_flows(config_steps)

        steps = []

        for number, step_config in config_steps.items():
            specs = self._visit_step(number, step_config)
            steps.extend(specs)

        return sorted(steps, key=attrgetter("step_num"))