protected async override void OnAppearing()
        {
            base.OnAppearing();
            DataTable     dt   = new DataTable();
            BackupHandler edf  = new BackupHandler();
            var           temp = (measunit)BindingContext;

            using (var stream = await FileSystem.OpenAppPackageFileAsync("MEASUNIT.EDF"))
            {
                using (var reader = new StreamReader(stream))
                {
                    dt = edf.readEDF(reader);
                    reader.Close();
                }
                stream.Close();
            }
        }