You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: store.go
    path of file: ./repos/mattermost/server/public/pluginapi/experimental/panel
    
    the code of the file until where you have to start completion: package panel

import (
	"errors"

	"github.com/mattermost/mattermost/server/public/pluginapi"
)

type Store interface {
	SetPanelPostID(userID str
    
func (ps *panelStore) SetPanelPostID(userID, postID string) error {
	ok, err := ps.kv.Set(ps.getKey(userID), postID)
	if err != nil {
		return err
	}
	if !ok {
		return errors.New("value not set without errors")
	}
	return nil
}