Single generator

yield.php

<?php
$generatorWithTwoWayCommunication = function()
{
    $randomValue = mt_rand();
    yield $randomValue;
    $receivedFromOuterSpace = yield;
    yield $receivedFromOuterSpace * $receivedFromOuterSpace;
    return $receivedFromOuterSpace * $randomValue;
};

$generator = $generatorWithTwoWayCommunication();
$valueFromFirstIteration = $generator->current();
$generator->next();
$valueFromSecondIteration = $generator->send(666);
$generator->next();
$valueReturnedFromGenerator = $generator->getReturn();