def get_queryset(self, pks):
raise NotImplementedError('<STR_LIT>')<EOL>
Construct a queryset using given primary keys.

        The cart is pretty much useless until this method is overriden.
        The default implementation just raises ``NotImplementedError``.

        Parameters
        ----------
        pks : list of str

        Returns
        -------
        django.db.models.query.QuerySet

        Examples
        --------
        In the most basic case this method may look like the one
        below::

            def get_queryset(self, pks):
                return Item.objects.filter(pk__in=pks)