public Variable FirstVariable()
{
Variable result = null;
if (this.head is IElement)
{
result = ((IElement)this.head).FirstVariable();
if (result != null)
return result;
}
if (this.tail is IElement)
result = ((IElement)this.tail).FirstVariable();
return result;
}
public void FirstVariable() { List list = new List(new Variable("H"), new Variable("T")); var result = list.FirstVariable(); Assert.IsNotNull(result); Assert.AreEqual("H", result.Name); }