gistfile1.txt

async function fibonacci(n){
    if (n < 0) throw new Error('must be 0 or greater');
    if (n === 0) return 0;
    if (n === 1) return 1;
    return await fibonacci(n - 1) + await fibonacci(n - 2);
 
}
function isPrime(num){
    for (let i = 2; i < num; i++)
        if (num % i === 0) return false;
    return num !== 1 && num !== 0;
}
function isEven(n) {
    return n % 2 == 0;
}
function isOdd(n) {
    return Math.abs(n % 2) == 1;
}

function toLowerCase(str){
    return str.toLowerCase();
}
function toUpperCase(str){
    return str.toUpperCase();
    //return "HELLO WORLD";
}
function contains(str, substring, fromIndex){
    return str.indexOf(substring, fromIndex) !== -1;
}
function repeat(str, n){
    return (new Array(n + 1)).join(str);
}

function simulateAsyncOpV1(callback){
 setTimeout(function () {
    callback();
 }, 1000);
}

function simulateAsyncOpV2(){
    return new Promise(function(resolve, reject) {
        resolve();
    });
}

function simulateAsyncOp() {
    return new Promise(resolve => {
        resolve(true);     
    });
}

module.exports = {
    fibonacci: fibonacci,
    isPrime: isPrime,
    isEven: isEven,
    isOdd: isOdd,
    toLowerCase: toLowerCase,
    toUpperCase: toUpperCase,	
    contains: contains,
    repeat: repeat,
    simulateAsyncOp: simulateAsyncOp
};