export declare function remove<T>(array: T[], ...items: T[]): void;
export declare function add<T>(array: T[], ...items: T[]): void;
export declare function ensure<T>(array: T[], ...items: T[]): void;
export declare function has<T>(array: T[], ...items: T[]): boolean;
export declare function first<T>(array: T[]): T | undefined;
export declare function last<T>(array: T[]): T | undefined;
export declare function copy<T>(array: T[]): T[];