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    var length = 10;
    function fn(n){}{
        console.log(this.length);
    }
    var obj = {
        length: 5,
        method: function( fn ){
            // this = obj
            fn(); // this = window  > 10
            arguments[0](); // this = arguments > 2
        }
    }
    obj.method(fn, 1)