Function itertools::chain

Important traits for Chain<A, B>

impl<A, B> Iterator for Chain<A, B> where
    A: Iterator,
    B: Iterator<Item = <A as Iterator>::Item>,  type Item = <A as Iterator>::Item;

pub fn chain<I, J>(
    i: I, 
    j: J
) -> Chain<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter> where
    I: IntoIterator,
    J: IntoIterator<Item = I::Item>, 

Create an iterator that first iterates i and then j.

IntoIterator enabled version of i.chain(j).

use itertools::chain;

for elt in chain(&[1, 2, 3], &[4]) {
    /* loop body */
}