ObjC/Swift Swift 里面的 `==` 有些奇怪的行为，明白的请帮忙解释一下...
var a = [1, 2, 3, 4, 5]
var b = [1, 2, 3, 4, 5]
a === b // false, as expected
a == b // true, as expected
a[0...1] // [1, 2]
b[0...1] // [1, 2]
a[0...1] === b[0...1] // false, as expected
a[0...1] == b[0...1] // false, surprise
// ...and some more confusion
var c = a[0...1]
var d = b[0...1]
c == d // true
为什么为什么这是为什么...
