Using Array#flat

Consider the following nested array. What will get logged?

const array = [1,[2,[3,[4,[5,[6,[7],8],9],10]]],12];
const result = array.flat(5);
console.log(result);

[1, 2, 3, 4, 5, 6, [7], 8, 9, 10, 12]

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12]