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: command_mq_balance.go
    path of file: ./repos/seaweedfs/weed/shell
    
    the code of the file until where you have to start completion: package shell

import (
	"context"
	"fmt"
	"github.com/seaweedfs/seaweedfs/weed/pb"
	"github.com/seaweedfs/seaweedfs/weed/pb/mq_pb"
	"io"
)

func init() {
	Commands = append(Commands, &commandMqBalanceTopics{})
}

type commandMqBalanceTopics struct {
}

func (c *commandMqBalanceTopics) Name() string {
	return "mq.balance"
}

func (c *commandMqBalanceTopics) Help() string {
	return `balance topic partitions

`
}

func (c *commandMqBalanceTopics) Do(args []string, commandEnv *CommandEnv, writer io.Writer) error {

	// find 
    
func (c *commandMqBalanceTopics) Do(args []string, commandEnv *CommandEnv, writer io.Writer) error {

	// find the broker balancer
	brokerBalancer, err := findBrokerBalancer(commandEnv)
	if err != nil {
		return err
	}
	fmt.Fprintf(writer, "current balancer: %s\n", brokerBalancer)

	// balance topics
	return pb.WithBrokerGrpcClient(false, brokerBalancer, commandEnv.option.GrpcDialOption, func(client mq_pb.SeaweedMessagingClient) error {
		_, err := client.BalanceTopics(context.Background(), &mq_pb.BalanceTopicsRequest{})
		if err != nil {
			return err
		}
		return nil
	})

}