export function shuffle(source) {
const arr = source.slice()
for (let i = 0; i < arr.length; i++) {
const j = getRandomInt(i)
swap(arr, i, j)
}
return arr
}
function getRandomInt(max) {
return Math.floor(Math.random() * (max + 1))
}
function swap(arr, i, j) {
const t = arr[i]
arr[i] = arr[j]
arr[j] = t
}