code: def MultiWritePathHistory(self, client_path_histories):
      
      for client_path, client_path_history in iteritems(client_path_histories):
        if client_path.client_id not in self.metadatas:
          raise db.UnknownClientError(client_path.client_id)
  
        path_info = rdf_objects.PathInfo(
            path_type=client_path.path_type, components=client_path.components)
  
        for timestamp, stat_entry in iteritems(client_path_history.stat_entries):
          path_record = self._GetPathRecord(
              client_path.client_id, path_info, set_default=False)
          if path_record is None:
            # TODO(hanuszczak): Provide more details about paths that caused that.
            raise db.AtLeastOneUnknownPathError([])
  
          path_record.AddStatEntry(stat_entry, timestamp)
  
        for timestamp, hash_entry in iteritems(client_path_history.hash_entries):
          path_record = self._GetPathRecord(
              client_path.client_id, path_info, set_default=False)
          if path_record is None:
            # TODO(hanuszczak): Provide more details about paths that caused that.
            raise db.AtLeastOneUnknownPathError([])
  
          path_record.AddHashEntry(hash_entry, timestamp)
docs: Writes a collection of hash and stat entries observed for given paths.