public function testFlattenWithDepth()
{
// No depth flattens recursively
$array = [['#foo', ['#bar', ['#baz']]], '#zap'];
$this->assertEquals(['#foo', '#bar', '#baz', '#zap'], Arr::flatten($array));
// Specifying a depth only flattens to that depth
$array = [['#foo', ['#bar', ['#baz']]], '#zap'];
$this->assertEquals(['#foo', ['#bar', ['#baz']], '#zap'], Arr::flatten($array, 1));
$array = [['#foo', ['#bar', ['#baz']]], '#zap'];
$this->assertEquals(['#foo', '#bar', ['#baz'], '#zap'], Arr::flatten($array, 2));
}