code: def update(self, vts):
      
      for vt in vts.versioned_targets:
        vt.ensure_legal()
        if not vt.valid:
          self._invalidator.update(vt.cache_key)
          vt.valid = True
          self._artifact_write_callback(vt)
      if not vts.valid:
        vts.ensure_legal()
        self._invalidator.update(vts.cache_key)
        vts.valid = True
        self._artifact_write_callback(vts)
docs: Mark a changed or invalidated VersionedTargetSet as successfully processed.