code: func (n *ReferenceDef) Accept(v Visitor) (Node, bool) {
  	newNode, skipChildren := v.Enter(n)
  	if skipChildren {
  		return v.Leave(newNode)
  	}
  	n = newNode.(*ReferenceDef)
  	node, ok := n.Table.Accept(v)
  	if !ok {
  		return n, false
  	}
  	n.Table = node.(*TableName)
  	for i, val := range n.IndexColNames {
  		node, ok = val.Accept(v)
  		if !ok {
  			return n, false
  		}
  		n.IndexColNames[i] = node.(*IndexColName)
  	}
  	onDelete, ok := n.OnDelete.Accept(v)
  	if !ok {
  		return n, false
  	}
  	n.OnDelete = onDelete.(*OnDeleteOpt)
  	onUpdate, ok := n.OnUpdate.Accept(v)
  	if !ok {
  		return n, false
  	}
  	n.OnUpdate = onUpdate.(*OnUpdateOpt)
  	return v.Leave(n)
  }
docs: // Accept implements Node Accept interface.