def start_response(self,status='200', headers=[], exec_info=None):
        self.response.status = str(status).split(' ', 1)[0]
        self.response.headers = dict(headers)
        return lambda *args, **kargs: \
            self.response.write(escape=False, *args, **kargs)
Unregister the SizedImage subclass currently assigned to `attr_name`.
dataset/ETHPy150Open uwdata/termite-visualizations/web2py/gluon/main.py/LazyWSGI.start_response--crossover with--dataset/ETHPy150Open WGBH/django-versatileimagefield/versatileimagefield/registry.py/VersatileImageFieldRegistry.unregister_sizer