pub fn split(string: String) -> Result<Vec<String>, mtk::ValueError> {
if string.contains(" ") {
let mut res: Vec<String> = Vec::new();
for e in string.split_whitespace() {
res.push(e.to_string());
}
Ok(res)
} else {
Err(mtk::ValueError::with_string(format!("nothing to split in '{}'", string)))
}
}