def find_filter(self, filter_name):
        if filter_name in self.filters:
            return self.filters[filter_name]
        else:
            raise TemplateSyntaxError(filter_name % "Invalid filter: '%s'")
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.3/django/template/base.py/Parser.find_filter/swapped operands of `%`