code: def extract_labels(self) -> np.ndarray:
          
          condition_idxs, epoch_idxs, _ = np.where(self)
          _, unique_epoch_idxs = np.unique(epoch_idxs, return_index=True)
          return condition_idxs[unique_epoch_idxs]
docs: Extract condition labels.
  
          Returns
          -------
          np.ndarray
              The condition label of each epoch.