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: migrations.go
    path of file: ./repos/incubator-answer/internal/migrations
    
    the code of the file until where you have to start completion: /*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package migrations

import (
	"context"
	"fmt"

	"github.com/apache/incubator-answer/internal/base/data"
	"github.com/apache/incubator-answer/internal/entity"
	"xorm.io/xorm"
)

const minDBVersion = 0

// Migration describes on migration from lower version to high version
type Migration interface {
	Version() string
	Description() string
	Migrate(ctx context.Context, x *xorm.Engine) error
	ShouldCleanCache() bool
}

type migration struct {
	version          string
	description      string
	migrate          func(ctx context.Context, x *xorm.Engine) error
	shouldCleanCache bool
}

// Version returns the migration's version
func (m *migration) Version() string {
	return m.version
}

// Description returns the migration's description
func (m *migration) Description() string {
	return m.description
}

// Migrate executes the migration
func (m *migration) Migrate(ctx context.Context, x *xorm.Engi
    
func Migrate(debug bool, dbConf *data.Database, cacheConf *data.CacheConf, upgradeToSpecificVersion string) error {
	cache, cacheCleanup, err := data.NewCache(cacheConf)
	if err != nil {
		fmt.Println("new cache failed:", err.Error())
	}
	engine, err := data.NewDB(debug, dbConf)
	if err != nil {
		fmt.Println("new database failed: ", err.Error())
		return err
	}
	defer engine.Close()

	currentDBVersion, err := GetCurrentDBVersion(engine)
	if err != nil {
		return err
	}
	expectedVersion := ExpectedVersion()
	if len(upgradeToSpecificVersion) > 0 {
		fmt.Printf("[migrate] user set upgrade to version: %s\n", upgradeToSpecificVersion)
		for i, m := range migrations {
			if m.Version() == upgradeToSpecificVersion {
				currentDBVersion = int64(i)
				break
			}
		}
	}

	for currentDBVersion < expectedVersion {
		fmt.Printf("[migrate] current db version is %d, try to migrate version %d, latest version is %d\n",
			currentDBVersion, currentDBVersion+1, expectedVersion)
		migrationFunc := migrations[currentDBVersion]
		fmt.Printf("[migrate] try to migrate Answer version %s, description: %s\n", migrationFunc.Version(), migrationFunc.Description())
		if err := migrationFunc.Migrate(context.Background(), engine); err != nil {
			fmt.Printf("[migrate] migrate to db version %d failed: %s\n", currentDBVersion+1, err.Error())
			return err
		}
		if migrationFunc.ShouldCleanCache() {
			if err := cache.Flush(context.Background()); err != nil {
				fmt.Printf("[migrate] flush cache failed: %s\n", err.Error())
			}
		}
		fmt.Printf("[migrate] migrate to db version %d success\n", currentDBVersion+1)
		if _, err := engine.Update(&entity.Version{ID: 1, VersionNumber: currentDBVersion + 1}); err != nil {
			fmt.Printf("[migrate] migrate to db version %d, update failed: %s", currentDBVersion+1, err.Error())
			return err
		}
		currentDBVersion++
	}
	if cache != nil {
		cacheCleanup()
	}
	return nil
}