/**
 * Makes the first character of a string uppercase
 */
export declare function upperFirst(str: string): string;
export declare function wait(ms: number): Promise<unknown>;
/**
 * Recursively merge two objects.
 * 递归合并两个对象。
 *
 * @param source The source object to merge from. 要合并的源对象。
 * @param target The target object to merge into. 目标对象，合并后结果存放于此。
 * @param mergeArrays How to merge arrays. Default is "replace".
 *        如何合并数组。默认为replace。
 *        - "union": Union the arrays. 对数组执行并集操作。
 *        - "intersection": Intersect the arrays. 对数组执行交集操作。
 *        - "concat": Concatenate the arrays. 连接数组。
 *        - "replace": Replace the source array with the target array. 用目标数组替换源数组。
 * @returns The merged object. 合并后的对象。
 */
export declare function deepMerge<T extends object | null | undefined, U extends object | null | undefined>(source: T, target: U, mergeArrays?: 'union' | 'intersection' | 'concat' | 'replace'): T & U;