def filesDir = $files.getFilesDir()
def file = $files.buildFile {
    setPath(filesDir, "tmp/aaa.txt")
}
file.writeText("hello world", "UTF-8")
def dest = $files.buildFile {
    setPath(filesDir, "tmp/bbb.txt")
}
$console.log(file.renameTo(dest))
$console.log(file.exists())
$console.log(dest.exists())
file.delete()
dest.delete()