/**
 * Converts the first character of string to upper case.
 *
 * @param {string} str - The string that is to be changed
 * @returns {string} - The converted string.
 *
 * @example
 * const convertedStr1 = upperFirst('fred') // returns 'Fred'
 * const convertedStr2 = upperFirst('Fred') // returns 'Fred'
 * const convertedStr3 = upperFirst('FRED') // returns 'FRED'
 */
declare function upperFirst<T extends string = string>(str?: T): Capitalize<T>;

export { upperFirst };