/**
 * 可以使指定的属性变成「可选的」
 * @example: PartialBy<{a: number}, 'a'> = {a?: number}
 */
export declare type PartialBy<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>;
/**
 * Formats data as a string. Usually the data is accessible throught the `this`
 * keyword.
 *
 * @param this
 *        Context to format
 *
 * @return Formatted text
 */
export declare type FormatterCallbackFunction<T> = (this: T) => string;