``` ~function(){ function myFlat(){ let result=[], _this = this; let fn = (arr)=>{ for (let i = 0; i < arr.length; i++) { const item = arr[i]; if(Array.isArray(item)){ fn(item); continue; } result.push(item); } } fn(_this); return result; } Array.prototype.myFlat = myFlat }() ```