var $ = (function(){
   var obj = {};
   return obj;
})();

$.each = function(collection,fn){

    if(collection.constructor.name === 'Array'){
        for(var i = 0; i < collection.length; i++){
            fn.call(this,collection[i]);
        }
    }else{
        for(var prop in collection){
            fn.call(this,collection[prop]);
        }
    }


};


$.each([1,2,3,7,8],function(num){
    console.log(num * 2);
});

$.each(['A','B','C'],function(char){
    console.log(char);
});

2
4
6
14
16
A
B
C