pub fn join<I>(iterable: I, sep: &str) -> Stringwhere
    I: IntoIterator,
    I::Item: Display,Expand description
Combine all iterator elements into one String, seperated by sep.
IntoIterator enabled version of iterable.join(sep).
use itertools::join;
assert_eq!(join(&[1, 2, 3], ", "), "1, 2, 3");