/**
 * Extracts the file extension from a provided string (filename or file path).
 *
 * @param filePath - The file path or filename string to extract extension from
 * @param options - Configuration options for the extraction
 * @param withoutDot - If true, returns extension without the dot prefix (default: false)
 * @returns The file extension with or without dot, or empty string if no extension found
 *
 * @example
 * ```typescript
 * getFileExtension('document.pdf') // Returns '.pdf'
 * getFileExtension('document.pdf', { withoutDot: true }) // Returns 'pdf'
 * getFileExtension('/path/to/file.txt') // Returns '.txt'
 * getFileExtension('file') // Returns ''
 * getFileExtension('archive.tar.gz') // Returns '.gz'
 * ```
 */
export declare function getFileExtension(filePath: string, withoutDot?: boolean): string;