public IObservable <DataDimension> GetDimension(string column)
 {
     return(_dimensions
            .TakeUntilDisable(this)
            .Where(dims => dims.Any(d => d.Column == column))
            .Select(dims => dims.FirstOrDefault(d => d.Column == column))
            .Take(1)
            .ObserveOnMainThread());
 }