function gen()

{

    $name = (yield 'hello');

    $nickname = (yield 'world');

    yield '!!!';

    echo $name;

    echo '---'.$nickname;

}

$gen = gen();

echo $gen->key(),':',$gen->current();//0:hello

echo $gen->key(),':',$gen->current();//0:hello

echo $gen->key(),':',$gen->send('jack');//0:world

echo $gen->key(),':',$gen->current();//1:world

echo $gen->key(),':',$gen->send('mysic');//!!!

echo $gen->key(),':',$gen->current();//!!!

echo $gen->key();//

echo $gen->current();//!!!

echo $gen->next();//jack---mysic

echo (int)$gen->valid();//0

echo $gen->key();//null

echo $gen->send('haha');//null

echo $gen->key();//null

echo $gen->current();//null

echo $gen->next();//null