规避同名冲突

function foo() {
    function bar(a) {
         i = 3;
        console.log(a + i);//3
    }
    console.log(i);//undefined
    for (var i = 0; i < 4; i++) {
        console.log(i);//0
        bar(i * 2);//执行了之后便f赋值为3
        console.log(i);//3
    }
    console.log(i);//4
}
foo();
function foo() {
    function bar(a) {