code: func (c *Ctx) WithDeadline(deadline time.Time) context.CancelFunc {
  	ctx, cf := context.WithDeadline(c.request.Context(), deadline)
  	c.request = c.request.WithContext(ctx)
  	return cf
  }
docs: // WithDeadline calls context.WithDeadline and automatically
  // updates context on the containing lars.Ctx object.