docs: def AddLabels(self, labels_names, owner=None):
      """Add labels to the AFF4Object."""
      if owner is None and not self.token:
        raise ValueError("Can't set label: No owner specified and "
                         "no access token available.")
      if isinstance(labels_names, string_types):
        raise ValueError("Label list can't be string.")
  
      owner = owner or self.token.username
  
      current_labels = self.Get(self.Schema.LABELS, self.Schema.LABELS())
      for label_name in labels_names:
        label = rdf_aff4.AFF4ObjectLabel(
            name=label_name, owner=owner, timestamp=rdfvalue.RDFDatetime.Now())
        current_labels.AddLabel(label)
  
      self.Set(current_labels)