code: func addPlanToResponse(parent PhysicalPlan, info *physicalPlanInfo) *physicalPlanInfo {
  	np := parent.Copy()
  	np.SetChildren(info.p)
  	return &physicalPlanInfo{p: np, cost: info.cost, count: info.count}
  }
docs: // addPlanToResponse creates a *physicalPlanInfo that adds p as the parent of info.