export interface Migrator<B, A> {
    upgrade(node: B): A;
    downgrade(node: A): B;
}
export interface MigratorDefinition<B, A> {
    upgrade?: (node: B, traverse: (node: any) => any) => A;
    downgrade?: (node: A, traverse: (node: any) => any) => B;
}
export interface MigratorsMap<B, A> {
    [key: string]: MigratorDefinition<B, A>;
}
export declare const DEFAULT: symbol;
export declare function createMigrator<B, A>(definition: MigratorsMap<B, A>): Migrator<B, A>;