let str = "";
for (let i = 0; i < 7; ++i) {
    str += "#";
    console.log(str)
}

// Nicer solution: use loop like
// for (let str = "#"; str.length < 8; str += "#")

for (let s = "#"; s.length < 8; s += "#") {
	console.log(s);
}

Add chapter 2, exercise 1
Add chapter 2, exercise 1
