code: func (p *basePlan) ReplaceParent(parent, newPar Plan) error {
  	for i, par := range p.parents {
  		if par.GetID() == parent.GetID() {
  			p.parents[i] = newPar
  			return nil
  		}
  	}
  	return SystemInternalErrorType.Gen("ReplaceParent Failed!")
  }
docs: // ReplaceParent means replace a parent for another one.