export declare function camelCase(str: string): string;
export declare function identity<T>(val: T): T;
export declare function isFinite(val: unknown): val is number;
export declare function isPlainObject(val: unknown): val is Record<string, any>;
export declare function isUndefined(val: unknown): val is undefined;
export declare function lowerFirst(str: string): string;
export declare function mapKeys(obj: Record<string, any>, fn: (value: any, key: string) => string): Record<string, any>;