我有對象的簡單對象： window.abilities = {
migrate:{
name:"Migrate",
description:"Move your tribe to another area; generate all new resources. Takes one time unit.",
image:"migrate
我有3個簡單的類CashRegister，Bill和Position。 CashRegister由Bill對象組成，Bill對象由Position對象組成。他們作爲跟隨 class CashRegister
def initialize
@bills = []
end
def product_frequency
#???
end
我定義了一個對象，如下所示： var obj = {};
var name = "nonenumerable";
var value = "hello world";
Object.defineProperty(obj, name, {value: value,
writable : true,
enumerable : false,
我有數組數組。假設我想統計出9箇中有多少元素等於"a"。 string[][] arr = new string[3][] {
new string[]{"a","b","c"},
new string[]{"d","a","f"},
new string[]{"g","a","a"}
};
我如何使用可枚舉擴展方法（Count，Where等），它做什麼？