const add = function(a, b) {
	return a + b;
};

const subtract = function(a, b) {
	return a - b;
};

const sum = function(array) {
	const output = array.reduce((total, value) => {
    return total + value;
  }, 0);
  return output;
};

const multiply = function(array) {
	const output = array.reduce((multiplification, value) => {
    return multiplification * value;
  }, 1);
  return output;
};

const power = function(a, x) {
	return 4 ** 3;
};

const factorial = function(a) {
	if (a <= 1) {
    return 1;
  }
  return a * factorial(a - 1);
};

// Do not edit below this line
module.exports = {
  add,
  subtract,
  sum,
  multiply,
  power,
  factorial
};