code: function forEach (obj, callback) {
  		if (!isFunction(callback)) return
  		if (isArray(obj)) {
  			if (obj.forEach) return obj.forEach(callback)
  			for (var i = 0; i < obj.length; ++i) {
  				callback(obj[i], i)
  			}
  		} 
  		else if (isObject(obj)) {
  			for (var key in obj) {
  				obj.hasOwnProperty(key) && callback(obj[key], key)
  			}
  		}
  	}
docs: util function