public bool IsNull(object key)
{
if (key is int && m_cd.Type == ValueType.Array)
{
IronJSONValue val = (IronJSONValue)m_cd.Array[(int)key];
return val.Type == ValueType.Null;
}
else if (key is string && m_cd.Type == ValueType.Object)
{
IronJSONValue val = m_cd.Obj[(string)key];
return val.Type == ValueType.Null;
}
else
throw new InvalidKeyException(key.ToString());
}