/**
 * Check and return true if an object is type of string
 */
export declare function isString(obj: any): boolean;
/**
 * Check and return true if an object not undefined or null
 */
export declare function isPresent(obj: any): boolean;
/**
 * Check and return true if an object is type of Function
 */
export declare function isFunction(obj: any): boolean;
/**
 * Create Image element with specified url string
 */
export declare function createImage(src: string): HTMLImageElement;
/**
 * Call the function
 */
export declare function callFun(fun: Function): any;