'Render an additional custom submit button for interim save,
which overrides the default _next to returns to an update
form for the same record after create/update'

@staticmethod
def _interim_save_button():

    label = current.deployment_settings.get_ui_interim_save()
    if label:
        _class = 'interim-save'
        if isinstance(label, basestring):
            label = current.T(label)
        elif (isinstance(label, (tuple, list)) and (len(label) > 1)):
            (label, _class) = label[:2]
        elif (not isinstance(label, lazyT)):
            label = current.T('Save    and    Continue    Editing')
        item = ('interim_save', label, _class)
    else:
        return
    settings = current.response.s3.crud
    if settings.custom_submit:
        settings.custom_submit.insert(0, item)
    else:
        settings.custom_submit = [item]
    return
