code: def set_labels(self, subj_labels):
          
          if len(subj_labels) != self.n_subjs:
              raise ValueError('The number of given labels is not the same as the number of subjects.')
  
          self.labels = subj_labels
docs: Parameters
          ----------
          subj_labels: list of int or str
              This list will be checked to have the same size as files list
              (self.items)