// @ts-check

/**
 * Calculates the sum of the two input arrays.
 *
 * @param {number[]} array1
 * @param {number[]} array2
 * @returns {number} sum of the two arrays
 */
export function twoSum(array1, array2) {
  throw new Error('Implement the twoSum function');
}

/**
 * Checks whether a number is a palindrome.
 *
 * @param {number} value
 * @returns {boolean}  whether the number is a palindrome or not
 */
export function luckyNumber(value) {
  throw new Error('Implement the luckyNumber function');
}

/**
 * Determines the error message that should be shown to the user
 * for the given input value.
 *
 * @param {string|null|undefined} input
 * @returns {string} error message
 */
export function errorMessage(input) {
  throw new Error('Implement the errorMessage function');
}
