code: def create_roles(apps, schema_editor):
      
      SystemWideEnterpriseRole = apps.get_model('enterprise', 'SystemWideEnterpriseRole')
      SystemWideEnterpriseRole.objects.update_or_create(name=ENTERPRISE_ADMIN_ROLE)
      SystemWideEnterpriseRole.objects.update_or_create(name=ENTERPRISE_LEARNER_ROLE)
docs: Create the enterprise roles if they do not already exist.