public static Block ToEntity(this BlockModel instance)
        {
            if (instance.IsNull())
            {
                return(null);
            }

            return(new Block
            {
                Announcements = instance.Announcements.SelectIfNotNull(x => x.ToEntity()).ToListIfNotNull(),
                Teachers = instance.Teachers.SelectIfNotNull(x => x.ToEntity()).ToListIfNotNull(),
                EndDate = instance.EndDate,
                StartDate = instance.StartDate,
                ClassCapacity = instance.ClassCapacity,
                Classes = instance.Classes.SelectIfNotNull(x => x.ToEntity()).ToListIfNotNull(),
                EnroledStudents = instance.EnroledStudents.SelectIfNotNull(x => x.ToEntity()).ToListIfNotNull(),
                Name = instance.Name,
                Id = instance.Id,
                MinutesPerClass = instance.MinutesPerClass,
                NumberOfClasses = instance.NumberOfClasses,
                Room = instance.Room.ToEntity(),
                IsInviteOnly = instance.IsInviteOnly
            });
        }