函数柯里化

函数柯里化，实现累加。

function f(){
    var arguList = [].slice.call(arguments); 
    var _fn = function (){
        arguList = arguList.concat([].slice.call(arguments));
        return _fn;
    }
    _fn.toString = function(){
        return arguList.reduce((i,j)=>i+j)
    }

    return _fn
}
console.log("%s",f(1)(2)(3)(3));