## prepend方法 将给定的值添加到集合的开头 将给定的值添加到集合的开头。 ~~~ $collection = collect([1, 2, 3, 4, 5]); $collection->prepend(0); $collection->all(); // [0, 1, 2, 3, 4, 5] ~~~ 也可以传递第二个参数来设置前置项的键 ~~~ $collection = collect(['one' => 1, 'two' => 2]); $collection->prepend(0, 'zero'); $collection->all(); // ['zero' => 0, 'one' => 1, 'two' => 2] ~~~