/**
 * @function
 * @description Convert a string to have the first letter in upper case and last letters in lower case.
 *
 * @param {string} str - The string to be modified.
 * @return {string} - The modified string with the first letter in upper case and last letters in lower case.
 *
 * @throws {TypeError} - If the input is not a string.
 */
export declare const convertStringCase: (str: string | any) => string;