__call__>> app_iter = self.application(environ, sr_checker)__call__>> environ, self.app)intercept_output>> app_iter = application(environ, replacement_start_response)__call__>> return self.application(environ, start_response)__call__>> return self.application(environ, start_response)__call__>> return self.handle_request( environ, start_response )handle_request>> kwargs = trans.request.params.mixed()paramsstr_paramsstr_POST__init__>> self.read_multi(environ, keep_blank_values, strict_parsing)read_multi>> environ, keep_blank_values, strict_parsing)__init__>> self.read_single()read_single>> self.file.seek(0)