In a punch clock application, a given Day has two foreign keys into the Punches table: PunchId_In and PunchId_Out. How can you annotate this relationship so Entity Framework creates it as intended? Note: One or both of these foreign keys may be undefined (null).

public class Day
{
    public int DayID { get; set; }
    public int? PunchId_In { get; set; }
    public int? PunchId_Out { get; set; }
    public virtual Punch PunchIn { get; set; }
    public virtual Punch PunchOut { get; set; }
}

public class Punch
{
    public int PunchId { get; set; }
    public DateTime PunchDT { get; set; }
}