def courses(self, request, pk=None):  # pylint: disable=invalid-name,unused-argument
        """
        Retrieve the list of courses contained within the catalog linked to this enterprise.

        Only courses with active course runs are returned. A course run is considered active if it is currently
        open for enrollment, or will open in the future.
        """
        enterprise_customer = self.get_object()
        self.check_object_permissions(request, enterprise_customer)
        self.ensure_data_exists(
            request,
            enterprise_customer.catalog,
            error_message="No catalog is associated with Enterprise {enterprise_name} from endpoint '{path}'.".format(
                enterprise_name=enterprise_customer.name,
                path=request.get_full_path()
            )
        )

        # We have handled potential error cases and are now ready to call out to the Catalog API.
        catalog_api = CourseCatalogApiClient(request.user, enterprise_customer.site)
        courses = catalog_api.get_paginated_catalog_courses(enterprise_customer.catalog, request.GET)

        # An empty response means that there was a problem fetching data from Catalog API, since
        # a Catalog with no courses has a non empty response indicating that there are no courses.
        self.ensure_data_exists(
            request,
            courses,
            error_message=(
                "Unable to fetch API response for catalog courses for "
                "Enterprise {enterprise_name} from endpoint '{path}'.".format(
                    enterprise_name=enterprise_customer.name,
                    path=request.get_full_path()
                )
            )
        )

        serializer = serializers.EnterpriseCatalogCoursesReadOnlySerializer(courses)

        # Add enterprise related context for the courses.
        serializer.update_enterprise_courses(enterprise_customer, catalog_id=enterprise_customer.catalog)
        return get_paginated_response(serializer.data, request)
Retrieve the list of courses contained within the catalog linked to this enterprise.

        Only courses with active course runs are returned. A course run is considered active if it is currently
        open for enrollment, or will open in the future.