var uniquePersons = persons.GroupBy(p => p.Email)
.Select(grp => grp.First())
.ToArray();
using(var dataModel = new DataModel())
{
var classes = dataModel.Attributes.Where(a => a.Field == "Class").Select(a => a.Key).Distinct().ToList();
}
if (!IsPostBack) {
GridView1.DataSource = GetProducts()
.GroupBy(o => new { o.Make, o.Model })
.Select(o => o.FirstOrDefault());
GridView1.DataBind();
}