public function test_chain_finite_streams_into_empty_stream()
{
$capture = function ($x) use(&$vals) {
$vals[] = $x;
};
$t = new Stream(10, function () {
return new Stream(20, function () {
return new Stream(30, function () {
return new Stream();
});
});
});
$vals = array();
$t->walk($capture);
$this->assertEquals(array(10, 20, 30), $vals);
}