docs: def apply_manual_indices(self, manual_indices):
          """Write to `self.manual`
  
          Write `manual_indices` to the boolean array `self.manual`
          and also store the indices as `self._man_root_ids`.
  
          Notes
          -----
          If `self.parent_changed` is `True`, i.e. the parent applied
          a filter and the child did not yet hear about this, then
          `HierarchyFilterError` is raised. This is important, because
          the size of the current filter would not match the size of
          the filtered events of the parent and thus index-mapping
          would not work.
          """
          if self.parent_changed:
              msg = "Cannot apply filter, because parent changed: " \
                    + "dataset {}. ".format(self.rtdc_ds) \
                    + "Run `RTDC_Hierarchy.apply_filter()` first!"
              raise HierarchyFilterError(msg)
          else:
              self._man_root_ids = list(manual_indices)
              cidx = map_indices_root2child(child=self.rtdc_ds,
                                            root_indices=manual_indices)
              if len(cidx):
                  self.manual[cidx] = False