#5 C# atom feed example does not work when doing cut and paste

[Joannes Vermorel]

There are a few (very simple) typos that prevent the C#
AtomFeed example from compiling when doing straight
cute-and-paste. It would be nice to clean them.

Also, you could include a line

using Atom.Core;

It would make the example totally complete.

Thanks in advance,
Joannes