docs: def labels(self, values):
          """Class labels (such as 1, 2, -1, 'A', 'B' etc.) for each sample in the dataset."""
          if isinstance(values, dict):
              if self.__data is not None and len(self.__data) != len(values):
                  raise ValueError(
                      'number of samples do not match the previously assigned data')
              elif set(self.keys) != set(list(values)):
                  raise ValueError('sample ids do not match the previously assigned ids.')
              else:
                  self.__labels = values
          else:
              raise ValueError('labels input must be a dictionary!')