def get_next_step(self, step=None):
        """
        Returns the next step after the given `step`. If no more steps are
        available, None will be returned. If the `step` argument is None, the
        current step will be determined automatically.
        """
        if step is None:
            step = self.steps.current
        form_list = self.get_form_list()
        keys = list(form_list.keys())
        key = keys.index(step) + 1
        for next_step in keys[key:]:
            if self.is_step_visible(next_step):
                return next_step
        return None
Returns the next step after the given `step`. If no more steps are
        available, None will be returned. If the `step` argument is None, the
        current step will be determined automatically.