box .net sdk. Use refresh token to get access token

I'm looking for a sample that shows how with the .NET SDK if you have a valid refresh token..how you might get an access token from it. I assume a new refresh token would come with that.

But I'm not seeing anything like that in the samples. Maybe there is some object that will take a refresh token as input and provide a connected box session.

Basically I'm trying to figure out how, once a user has authenticated and we have a refresh token....if the program a day later wants to do some work. How would we use that stored refresh token to do some work on box.