docs: def r_date_num(obj, multiple=False):
      """Read date-value table."""
      if isinstance(obj, (list, tuple)):
          it = iter
      else:
          it = LinesIterator
      if multiple:
          datasets = {}
          for line in it(obj):
              label = line[2]
              if label not in datasets:
                  datasets[label] = Dataset([Dataset.DATE, Dataset.FLOAT])
                  datasets[label].name = label
              datasets[label].parse_elements(line[0:2])
          return datasets.values()
      dataset = Dataset([Dataset.DATE, Dataset.FLOAT])
      return dataset.load(it(obj))