/**

* @function Factorial

* @description function to find factorial using recursion.

* @param {Integer} n - The input integer

* @return {Integer} - Factorial of n.

* @see [Factorial](https://en.wikipedia.org/wiki/Factorial)

* @example 5! = 1*2*3*4*5 = 120

* @example 2! = 1*2 = 2

*/

const factorial = (n) => {

if (!Number.isInteger(n) || n < 0) {

throw new RangeError('Input should be a non-negative whole number')

}

if (n === 0) {

return 1

}

return n * factorial(n - 1)

}

export { factorial }