What happens when you add a member to an `ExpandoObject` and then enumerate it as `IDictionary<string, object>`?
dynamic e = new ExpandoObject();
e.Name = "Ada";
e.Age = 36;
var dict = (IDictionary<string, object>)e;
Console.WriteLine(dict.Count);
dict.Remove("Age");
Console.WriteLine(((dynamic)e).Age);