/**
 * Converts the first character of string to upper case.
 *
 * @param str - The string that is to be changed
 * @returns The converted string.
 *
 * @example
 * const convertedStr1 = upperFirst('fred') // returns 'Fred'
 * const convertedStr2 = upperFirst('Fred') // returns 'Fred'
 * const convertedStr3 = upperFirst('FRED') // returns 'FRED'
 */
export function upperFirst(str: string): string {
  return str.substring(0, 1).toUpperCase() + str.substring(1);
}
