/**
 * Perform shallow extend of a target object with only this extension's properties which doesn't exist in the target.
 *
 * TODO: Maybe it should be moved to global helpers? It's changed `extend` function.
 *
 * @param {object} target An object that will receive the new properties.
 * @param {object} extension An object containing additional properties to merge into the target.
 * @returns {object}
 */
export declare function extendNotExistingKeys(target: Record<string, unknown>, extension: Record<string, unknown>): Record<string, unknown>;
/**
 * Create range of values basing on cell indexes. For example, it will create below ranges for specified function arguments:
 *
 * createCellHeadersRange(2, 7) => `2-7`
 * createCellHeadersRange(7, 2) => `2-7`
 * createCellHeadersRange(0, 4, 'A', 'D') => `A-D`
 * createCellHeadersRange(4, 0, 'D', 'A') => `A-D`.
 *
 * @param {number} firstRowIndex Index of "first" cell.
 * @param {number} nextRowIndex Index of "next" cell.
 * @param {*} fromValue Value which will represent "first" cell.
 * @param {*} toValue Value which will represent "next" cell.
 * @returns {string} Value representing range i.e. A-Z, 11-15.
 */
export declare function createCellHeadersRange(firstRowIndex: number, nextRowIndex: number, fromValue?: string | number, toValue?: string | number): string;
/**
 * Normalize language code. It takes handled languageCode proposition and change it to proper languageCode.
 * For example, when it takes `eN-us` as parameter it return `en-US`.
 *
 * @param {string} languageCode Language code for specific language i.e. 'en-US', 'pt-BR', 'de-DE'.
 * @returns {string}
 */
export declare function normalizeLanguageCode(languageCode: string): string;
/**
 *
 * Warn user if there is no registered language.
 *
 * @param {string} languageCode Language code for specific language i.e. 'en-US', 'pt-BR', 'de-DE'.
 */
export declare function warnUserAboutLanguageRegistration(languageCode: string): void;