What is generator in PHP?

A generator is basically a normal function, but instead of returning a value it yields as many values as it needs to. It looks like a function but acts as an iterator. Generators use the yield keyword instead of return.

Sample Example - 

<?php
function generator() {
    echo "Generator started"; 
    for ($i = 0; $i < 5; ++$i) {
        yield $i;
        echo "Yielded $in";
    }
    echo "Generator ended"; 
}

foreach (generator() as $g);