@examon - you also should filter on the `cls` being passed in to match `x[1]`.  I.e. if one is reading with `NDData.read(..)` you don't want to display the `Table` readers.  Right now there are only `Table` readers, but in future this will change.  I'm guessing something like `(x[0] for x in funcs where x[1] is cls)` will work.