code: def _read_data(self, dataset, format=None):
          
          # Attempt to detect file format if "format" isn't specified
          if not format:
              format_class = formats.detect(dataset)
          else:
              if format not in formats.AVAILABLE.keys():
                  raise ValueError("'{0}' format not supported.".format(format))
              format_class = formats.AVAILABLE[format]
          return format_class(dataset).to_iterable()
docs: Reads a data file and returns and iterable that can be used as
          testing or training data.