false); static::assertSame('hello', Iter\first_key($actual)); static::assertSame('world', Iter\last_key($actual)); static::assertFalse(Iter\first($actual)); static::assertFalse(Iter\last($actual)); } public function testFromKeysWithNonArrayKeyKeys(): void { $actual = Iter\from_keys([ [1, 'hello'], [2, 'world'] ], static fn (array $k) => $k[1]); static::assertSame([1, 'hello'], Iter\first_key($actual)); static::assertSame([2, 'world'], Iter\last_key($actual)); static::assertSame('hello', Iter\first($actual)); static::assertSame('world', Iter\last($actual)); } }