docs: def _load(self):
          """ Load provenance info from the main store. """
          graph = self.context.parent.graph.get_context(self.context.identifier)
          data = {}
          for (_, p, o) in graph.triples((self.context.identifier, None, None)):
              if not p.startswith(META):
                  continue
              name = p[len(META):]
              data[name] = o.toPython()
          return data