val data = arrayOf("one", null, "three", "four", null)
// 将非空字符串转换为其长度，并添加索引信息, 带索引的非空字符串长度: [0_3, 2_5, 3_4]
data.mapIndexedNotNull { index, word ->
    if (word != null) {
        "$index" + "_" + word.length
    } else {
        null
    }
}.forEach {
    _console.log(it)
}