1. let objectFactory = function(constr) {
    2.     if(typeof constr !== "function") {
    3.       throw "first parameter must be function"
    4.   }
    5.   let newObj = Object.create(constr.prototype)
    6.   let arg = [].slice.call(arguments,1)
    7.   let ret = constr.apply(newObj,arg)
    8.   let isObject = typeof ret === "object" && ret !== null
    9.   let isFunction = typeof ret === "function"
    10.   if(isObject || isFunction) {
    11.       return ret
    12.   }
    13.   return newObj
    14. }