old_contents: import os
  from django.db import models
  from plstackapi.core.models import PlCoreBase
  from plstackapi.core.models import Slice
  from plstackapi.openstack.driver import OpenStackDriver
  
  # Create your models here.
  
  class Subnet(PlCoreBase):
      subnet_id = models.CharField(max_length=256, unique=True)
      cidr = models.CharField(max_length=20)
      ip_version = models.IntegerField()
      start = models.IPAddressField()
      end = models.IPAddressField()
      slice = models.ForeignKey(Slice, related_name='subnet')
  
      def __unicode__(self):  return u'%s' % (self.name)
  
  
new_contents: import os
  from django.db import models
  from plstackapi.core.models import PlCoreBase
  from plstackapi.core.models import Slice
  from plstackapi.openstack.driver import OpenStackDriver
  
  # Create your models here.
  
  class Subnet(PlCoreBase):
      subnet_id = models.CharField(max_length=256, unique=True)
      cidr = models.CharField(max_length=20)
      ip_version = models.IntegerField()
      start = models.IPAddressField()
      end = models.IPAddressField()
      slice = models.ForeignKey(Slice, related_name='subnet')
  
      def __unicode__(self):  return u'%s' % (self.slice.name)
  
  
subject: fix bug