public static IQueryable<Apprenticeship> WithProviderOrEmployerId(
            this IQueryable<Apprenticeship> apprenticeships, IEmployerProviderIdentifier identifier)
        {
            if (identifier.ProviderId.HasValue)
            {
                return apprenticeships.Where(app => app.Cohort.ProviderId == identifier.ProviderId);
            }

            return identifier.EmployerAccountId.HasValue ? 
                apprenticeships.Where(app => app.Cohort.EmployerAccountId == identifier.EmployerAccountId) : apprenticeships;
        }
 public static IQueryable<Apprenticeship> WithAlerts(
     this IQueryable<Apprenticeship> apprenticeships, bool hasAlerts,
     IEmployerProviderIdentifier identifier)
 {
     return identifier.ProviderId.HasValue ? WithAlertsProvider(apprenticeships, hasAlerts) : WithAlertsEmployer(apprenticeships, hasAlerts);
 }