public void WriteWithAtTest()
{
var document = new CsvDocument(new string[] { "name", "age" });
document.Write("Light", 18);
document.Write("Misa", 20);
document.WriteAtWith(0, new { Name = "Ryuk", Age = 999 });
Assert.IsFalse(document.IsEmpty);
Assert.AreEqual(3, document.Count);
}