generator.php

// a complex iterator
function gen() {
	$pagesize = 50;
	while( $items = $someapi->paginated_operation($pagesize) ) {
		foreach( $items as $item ) {
			yield $item;
		}
	}
}

// hidden by a simple function
foreach(gen() as $item) {
	do_a_thing($item);
}

// you could have 50,000 paginated results, but you only fetch a small batch as-needed
// and you only need to expose a function call.