private async Task <IEnumerable <Agendadata> > GetAgenda()
        {
            var agenda = await _storage.GetAgenda(FILENAME);

            if (agenda == null)
            {
                await _storage.SaveAgendaData(new Agendadata[] {
                    new Agendadata {
                        MessageId = 1, Titel = "agendatitel", CostumerId = 1, Description = "agendadescriptie", StartDate = "11/11/2017", EndDate = "12/11/2017", StartTime = "11:11:11", EndTime = "12:12:12", Priority = "High", State = "pending"
                    },
                    new Agendadata {
                        MessageId = 2, Titel = "agendatitel", CostumerId = 1, Description = "agendadescriptie", StartDate = "11/11/2017", EndDate = "12/11/2017", StartTime = "11:11:11", EndTime = "12:12:12", Priority = "High", State = "pending"
                    },
                    new Agendadata {
                        MessageId = 3, Titel = "agendatitel", CostumerId = 1, Description = "agendadescriptie", StartDate = "11/11/2017", EndDate = "12/11/2017", StartTime = "11:11:11", EndTime = "12:12:12", Priority = "High", State = "pending"
                    }
                }
                                              , FILENAME);
            }

            return(agenda);
        }