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: usernames_service_impl.go
    path of file: ./repos/teamgram-server/app/bff/usernames/internal/server/grpc/service
    
    the code of the file until where you have to start completion: /*
 * WARNING! All changes made in this file will be lost!
 * Created from 'scheme.tl' by 'mtprotoc'
 *
 * Copyright 2022 Teamgram Authors.
 *  All rights reserved.
 *
 * Author: teamgramio (teamgram.io@gmail.com)
 */

package service

import (
	"context"

	"github.com/teamgram/proto/mtproto"
	"github.com/teamgram/teamgram-server/app/bff/usernames/i
    
func (s *Service) AccountCheckUsername(ctx context.Context, request *mtproto.TLAccountCheckUsername) (*mtproto.Bool, error) {
	c := core.New(ctx, s.svcCtx)
	c.Logger.Debugf("account.checkUsername - metadata: %s, request: %s", c.MD.DebugString(), request.DebugString())

	r, err := c.AccountCheckUsername(request)
	if err != nil {
		return nil, err
	}

	c.Logger.Debugf("account.checkUsername - reply: %s", r.DebugString())
	return r, err
}