/**
* @param array|\iterator $peopleKeyedById
* @return array
*/
function exampleExtractKeys3($peopleKeyedById)
{
$keys = Sequence::make($peopleKeyedById)->map(fn\fnSwapParamsPassThrough(fn\fnIdentity()))->values()->to_a();
return $keys;
}
/**
* Generate a function that swaps the order of the parameters and calls $fn
*
* @param callable $fn
* @return callable
*/
public static function fnSwapParamsPassThrough($fn)
{
return fn\fnSwapParamsPassThrough($fn);
}