def _process_mrk_acc_view_for_equiv(self, limit):
        """
        Add the equivalences, either sameAs or equivalentClass,
        depending on the nature of the marker.
        We only process the ENSEMBL genes and NCBI gene ids.
        :param limit:
        :return:

        """
        if self.test_mode:
            graph = self.testgraph
        else:
            graph = self.graph
        model = Model(graph)
        # pass through the file again,
        # and make the equivalence statements to a subset of the idspaces.
        # TODO verify the difference between what the
        # mrk_acc_view vs mrk_summary_view buys us here.
        # if nothing, then we should remove one or the other.
        LOG.info("mapping marker equivalent identifiers in mrk_acc_view")
        line_counter = 0
        with open('/'.join((self.rawdir, 'mrk_acc_view')), 'r') as f:
            f.readline()  # read the header row; skip
            for line in f:
                line = line.rstrip("\n")
                line_counter += 1
                (accid, prefix_part, logicaldb_key, object_key,
                 preferred, organism_key) = line.split('\t')

                if self.test_mode is True:
                    if int(object_key) not in self.test_keys.get('marker'):
                        continue

                # right now not caring about other organisms
                if organism_key != 1:
                    continue

                mgiid = self.idhash['marker'].get(object_key)
                if mgiid is None:
                    # presumably we've already added the relevant MGI ids,
                    # so skip those that we can't find
                    LOG.debug("can't find mgiid for %s", object_key)
                    continue
                marker_id = None
                if preferred == '1':  # TODO what does it mean if it's 0?
                    if logicaldb_key == '55':  # entrez/ncbi
                        marker_id = 'NCBIGene:' + accid
                    elif logicaldb_key == '1' and prefix_part != 'MGI:':
                        marker_id = accid
                    elif logicaldb_key == '60':
                        marker_id = 'ENSEMBL:'+accid
                    # TODO get non-preferred ids==deprecated?

                if marker_id is not None:
                    if mgiid in self.markers['classes']:
                        model.addClassToGraph(marker_id, None)
                        model.addEquivalentClass(mgiid, marker_id)
                    elif mgiid in self.markers['indiv']:
                        model.addIndividualToGraph(marker_id, None)
                        model.addSameIndividual(mgiid, marker_id)
                    else:
                        LOG.error("mgiid not in class or indiv hash %s", mgiid)

                if not self.test_mode and limit is not None and line_counter > limit:
                    break

        return
Add the equivalences, either sameAs or equivalentClass,
        depending on the nature of the marker.
        We only process the ENSEMBL genes and NCBI gene ids.
        :param limit:
        :return: