THis method gets called when the next step/form should be rendered.
        `form` contains the last/current form.

def render_next_step(self, form, **kwargs):
        """
        THis method gets called when the next step/form should be rendered.
        `form` contains the last/current form.
        """
        # get the form instance based on the data from the storage backend
        # (if available).
        next_step = self.steps.next
        new_form = self.get_form(next_step,
            data=self.storage.get_step_data(next_step),
            files=self.storage.get_step_files(next_step))

        # change the stored current step
        self.storage.current_step = next_step
        return self.render(new_form, **kwargs)