code: func (p *PhysicalUnionScan) matchProperty(prop *requiredProperty, childPlanInfo ...*physicalPlanInfo) *physicalPlanInfo {
  	limit := prop.limit
  	res := p.GetChildByIndex(0).(PhysicalPlan).matchProperty(convertLimitOffsetToCount(prop), childPlanInfo...)
  	np := *p
  	np.SetChildren(res.p)
  	res.p = &np
  	if limit != nil {
  		res = addPlanToResponse(limit, res)
  	}
  	return res
  }
docs: // matchProperty implements PhysicalPlan matchProperty interface.