How to use the @adonisjs/ace.flags.number function in @adonisjs/ace

/**
 * The command is meant to migrate the database by execute migrations
 * in `up` direction.
 */
@inject([null, 'Adonis/Lucid/Database'])
export default class Migrate extends MigrationsBase {
  public static commandName = 'migration:rollback'
  public static description = 'Rollback migrations to a given batch number'

  @flags.string({ description: 'Define a custom database connection' })
  public connection: string

  @flags.boolean({ description: 'Print SQL queries, instead of running the migrations' })
  public dryRun: boolean

  @flags.number({
    description: 'Define custom batch number for rollback. Use 0 to rollback to initial state',
  })
  public batch: number

  /**
   * This command loads the application, since we need the runtime
   * to find the migration directories for a given connection
   */
  public static settings = {
    loadApp: true,
  }

  constructor (app: ApplicationContract, private _db: DatabaseContract) {
    super(app)
  }