def METHOD_NAME(self, cls_or_obj: WidgetType) -> WidgetType:
    """Set border & corner chars of cls_or_obj to self values"""
    # We cannot import any widgets into here due to cyclic imports,
    # so we have to "hack" around it.
    if not hasattr(cls_or_obj, "set_char"):
        raise NotImplementedError(
            f"Object of type {cls_or_obj} does not support `set_char`"
        )
    cls_or_obj.set_char("border", self.borders)
    cls_or_obj.set_char("corner", self.corners)
    return cls_or_obj