code: func (sh *Handler) Describe(ctx context.Context, dr *DescribeRequest) (dres *DescribeResponse, err error) {
  	sh.index.RLock()
  	defer sh.index.RUnlock()
  
  	return sh.DescribeLocked(ctx, dr)
  }
docs: // Describe returns a response for the given describe request. It acquires RLock
  // on the Handler's index.