export declare function normalizeExtension(extension: string): string;
export declare function getExtension(filename: string): string;
export declare function isCompressedExtension(extension: string): boolean;
export declare function isDocumentExtension(extension: string): boolean;
export declare function isMediaExtension(extension: string): boolean;
export declare function isImageExtension(extension: string): boolean;
export declare function isExecutableExtension(extension: string): boolean;
export declare function getCategoryFromExtension(extension: string): string;
export declare function getDoubleExtension(filename: string): string | null;