code: def set_placeholder(self, key, value):
          
          self._set('set-placeholder', '%s=%s' % (key, value), multi=True)
  
          return self
docs: Placeholders are custom magic variables defined during configuration
          time.
  
          .. note:: These are accessible, like any uWSGI option, in your application code via
              ``.runtime.environ.uwsgi_env.config``.
  
          :param str|unicode key:
  
          :param str|unicode value: