public function testIsValidRange()
{
$r = new Reference();
$pass = 2002002002;
$fail1 = 2002002;
$fail2 = 2002002002002;
$this->assertFalse($r->isValidRange([]));
$this->assertFalse($r->isValidRange([0]));
$this->assertFalse($r->isValidRange([0, 0, 0]));
$this->assertTrue($r->isValidRange([$pass, $pass]));
$this->assertFalse($r->isValidRange([$pass, $fail1]));
$this->assertFalse($r->isValidRange([$fail2, $pass]));
}