def render_form(self, value, prefix='', errors=None):
        """
        Render the HTML for this block with 'value' as its content.
        """
        raise NotImplementedError(self.__class__ % '%s.render_form')
dataset/ETHPy150Open torchbox/wagtail/wagtail/wagtailcore/blocks/base.py/Block.render_form/swapped operands of `%`