def as_checks(self, tmpl=TMPL, _items=None, **kwargs):
attrs = self.extra.copy()<EOL>attrs.update(kwargs)<EOL>attrs['<STR_LIT:type>'] = '<STR_LIT>'<EOL>attrs['<STR_LIT:name>'] = self.name<EOL>html = []<EOL>tmpl = to_unicode(tmpl)<EOL>values = self.to_string(**attrs) or []<EOL>items = _items or self.items<EOL>for item in items:<EOL><INDENT>if isinstance(item, list):<EOL><INDENT>html.extend(self._render_fieldset(item, attrs, values, tmpl))<EOL><DEDENT>else:<EOL><INDENT>html.append(self._render_item(item, attrs, values, tmpl))<EOL><DEDENT><DEDENT>return Markup('<STR_LIT:\n>'.join(html))<EOL>
Render the field as a series of checkboxes, using the `tmpl`
        parameter as the template for each item.

        :param tmpl:
            HTML template to use for rendering each item.

        :param **kwargs:
            Named paremeters used to generate the HTML attributes of each item.
            It follows the same rules as `get_html_attrs`