new_contents: # -*- coding: utf-8 -*-
  from __future__ import unicode_literals
  
  from django.db import models, migrations
  import django.db.models.deletion
  
  
  class Migration(migrations.Migration):
  
      dependencies = [
          ('catalogue', '0004_auto_20150217_1710'),
      ]
  
      operations = [
          migrations.AlterField(
              model_name='product',
              name='product_class',
              field=models.ForeignKey(related_name='products', on_delete=django.db.models.deletion.PROTECT, blank=True, to='catalogue.ProductClass', help_text='Choose what type of product this is', null=True, verbose_name='Product type'),
          ),
      ]
  
subject: Add migration that allows product_class FK to be blank