export declare class Str {
    /**
     * Empty string constant.
     * @type {String}
     */
    static readonly EMPTY: string;
    /**
     * Returns whether the given value is a string
     * @param  {string}  value the value to check
     * @return {boolean}       True if the value is of type string, otherwise false
     */
    static isString(value: any): boolean;
    /**
     * Returns whether the given string is NOT an empty string.
     * @param  {string}  string The string to check
     * @return {boolean}        True if the string is not empty, otherwise false.
     */
    static isNotEmptyString(string: string): boolean;
    /**
     * Returns whether the given string is an empty string
     * @param  {string}  string The string to check
     * @return {boolean}        True if the string is empty, otherwise false
     */
    static isEmptyString(string: string): boolean;
    /**
     * Formats the given string by inserting tokens according to the
     * tokenized location of string indices, "{N}", in n-order.
     * @param  {string}             formatString The string with tokenized string indices
     * @param  {(string|number)[]}  ...tokens    The strings to insert at each tokenized index
     * @return {string}                          The formatted string
     */
    static stringFormat(formatString: string, ...tokens: (string | number)[]): string;
}