old_contents: import json
  
  from spillway.query import GeoQuerySet
  from spillway.models import GeoManager
  from django.contrib.gis.db import models
  from model_utils.managers import PassThroughManager
  
  _geom = {
      'type': 'Polygon',
      'coordinates': [[
          [ -64.95, -31.42 ],
          [ -61.69, -28.22 ],
          [ -61.61, -32.39 ],
          [ -64.95, -31.42 ]
      ]]
  }
  
  
  class Location(models.Model):
      name = models.CharField(max_length=30)
      geom = models.GeometryField()
      #objects = models.GeoManager()
      #objects = PassThroughManager.for_queryset_class(GeoQuerySet)()
      objects = GeoManager()
  
      def __str__(self):
          return self.name
  
      @classmethod
      def create(cls, **defaults):
          data = {'name': 'Valhalla',
                  'geom': json.dumps(defaults.pop('geom', _geom))}
          data.update(**defaults)
          obj = cls(**data)
          obj.save()
          return obj
  
new_contents: import json
  
  from spillway.query import GeoQuerySet
  from spillway.models import GeoManager
  from django.contrib.gis.db import models
  
  _geom = {
      'type': 'Polygon',
      'coordinates': [[
          [ -64.95, -31.42 ],
          [ -61.69, -28.22 ],
          [ -61.61, -32.39 ],
          [ -64.95, -31.42 ]
      ]]
  }
  
  
  class Location(models.Model):
      name = models.CharField(max_length=30)
      geom = models.GeometryField()
      objects = GeoManager()
  
      def __str__(self):
          return self.name
  
      @classmethod
      def create(cls, **defaults):
          data = {'name': 'Vancouver',
                  'geom': json.dumps(defaults.pop('geom', _geom))}
          data.update(**defaults)
          obj = cls(**data)
          obj.save()
          return obj
  
subject: Remove unused import