code: func (c *requestContextMap) Get(req *http.Request) (Context, bool) {
  	c.lock.Lock()
  	defer c.lock.Unlock()
  	context, ok := c.contexts[req]
  	return context, ok
  }
docs: // Get returns the context associated with the given request (if any), and true if the request has an associated context, and false if it does not.
  // Get will only return a valid context when called from inside the filter chain set up by NewRequestContextFilter()