$map: ( key1: value1, key2: ( key-1: value-1, key-2: value-2, ), key3: value3);
这样嵌套map,调用时怎么调用嵌套的每个值呢?
一层嵌套的就直接map-get($map, key1),两层嵌套的就map-get(map-get($map, key2), key-1),以此类推...