def render(self, data=None, add_context=None):
        """Renders the widget as HTML."""
        template = loader.get_template(self.template)

        if not data:
            data = self.context(self.prepare_data())

        if add_context is not None:
            for key, value in add_context.iteritems():
                if key in self.accepted_keywords:
                    data[key] = value

        return template.render(data)
Renders the widget as HTML.