最后一题: function sum(){     var num=0;     Object.values(arguments).map(i=>{return num+=i})     return function su(){         if(arguments[0]){             Object.values(arguments).map(i=>{return num+=i})             return su         }else{             return num;         }     } } console.log(sum(1)(4)(6)()) console.log(sum(1,2,3)(11)()) console.log(sum(1,2,3)(12)(1,2,3)()) console.log(sum(1,2,3)())