def visitQualifier(self, ctx: ShExDocParser.QualifierContext):
        """ qualifier: includeSet | extraPropertySet | KW_CLOSED """
        if ctx.includeSet():
            if self.shape.inherit is None:
                self.shape.inherit = []
            self.shape.inherit += [self.context.tripleexprlabel_to_iriref(tel)
                                   for tel in ctx.includeSet().tripleExpressionLabel()]
        elif ctx.extraPropertySet():
            if self.shape.extra is None:
                self.shape.extra = []
            self.shape.extra += [self.context.predicate_to_IRI(p) for p in ctx.extraPropertySet().predicate()]

        elif ctx.KW_CLOSED():
            self.shape.closed = True