code: def get_key_name(self, environ, response_interception, exception=None):
          
          status = response_interception.get('status')
          status_code = status.split()[0]  # Leave only the status code.
          # PATH_INFO can be empty, so falling back to '/' in that case
          path = CHAR_RE.sub(self.separator, (environ['PATH_INFO'].rstrip('\/') or '/')[1:])
          parts = [path, environ['REQUEST_METHOD'], status_code]
          if exception:
              parts.append(exception.__class__.__name__)
          return '.'.join(parts)
docs: Get the timer key name.
  
          :param environ: wsgi environment
          :type environ: dict
          :param response_interception: dictionary in form
              {'status': '<response status>', 'response_headers': [<response headers], 'exc_info': <exc_info>}
              This is the interception of what was passed to start_response handler.
          :type response_interception: dict
          :param exception: optional exception happened during the iteration of the response
          :type exception: Exception
  
          :return: string in form '{{UNDERSCORED_PATH}}.{{METHOD}}.{{STATUS_CODE}}'
          :rtype: str