old_contents: #-*- coding: utf-8 -*-
  try:
      from django.contrib.auth import get_user_model
      User = get_user_model()
  except ImportError:
      from django.contrib.auth.models import User  # NOQA
  from django.db import models
  from django.utils.translation import ugettext_lazy as _
  from filer.models import filemodels
  
  
  class Clipboard(models.Model):
      user = models.ForeignKey(User, verbose_name=_('user'), related_name="filer_clipboards")
      files = models.ManyToManyField(
                          'File', verbose_name=_('files'), related_name="in_clipboards",
                          through='ClipboardItem')
  
      def append_file(self, file_obj):
          try:
              # We have to check if file is already in the clipboard as otherwise polymorphic complains
              self.files.get(pk=file_obj.pk)
              return False
          except filemodels.File.DoesNotExist:
              newitem = ClipboardItem(file=file_obj, clipboard=self)
              newitem.save()
              return True
  
      def empty(self):
          for item in self.bucket_items.all():
              item.delete()
      empty.alters_data = True
  
      def __unicode__(self):
          return u"Clipboard %s of %s" % (self.id, self.user)
  
      class Meta:
          app_label = 'filer'
          verbose_name = _('clipboard')
          verbose_name_plural = _('clipboards')
  
  
  class ClipboardItem(models.Model):
      file = models.ForeignKey('File', verbose_name=_('file'))
      clipboard = models.ForeignKey(Clipboard, verbose_name=_('clipboard'))
  
      class Meta:
          app_label = 'filer'
          verbose_name = _('clipboard item')
          verbose_name_plural = _('clipboard items')
  
new_contents: #-*- coding: utf-8 -*-
  try:
      from django.contrib.auth import get_user_model
      User = get_user_model()
  except ImportError:
      from django.contrib.auth.models import User  # NOQA
  from django.db import models
  from django.utils.translation import ugettext_lazy as _
  from filer.models import filemodels
  
  
  class Clipboard(models.Model):
      user = models.ForeignKey(User, verbose_name=_('user'), related_name="filer_clipboards")
      files = models.ManyToManyField(
                          'File', verbose_name=_('files'), related_name="in_clipboards",
                          through='ClipboardItem')
  
      def append_file(self, file_obj):
          try:
              # We have to check if file is already in the clipboard as otherwise polymorphic complains
              self.files.get(pk=file_obj.pk)
              return False
          except filemodels.File.DoesNotExist:
              newitem = ClipboardItem(file=file_obj, clipboard=self)
              newitem.save()
              return True
  
      def __unicode__(self):
          return u"Clipboard %s of %s" % (self.id, self.user)
  
      class Meta:
          app_label = 'filer'
          verbose_name = _('clipboard')
          verbose_name_plural = _('clipboards')
  
  
  class ClipboardItem(models.Model):
      file = models.ForeignKey('File', verbose_name=_('file'))
      clipboard = models.ForeignKey(Clipboard, verbose_name=_('clipboard'))
  
      class Meta:
          app_label = 'filer'
          verbose_name = _('clipboard item')
          verbose_name_plural = _('clipboard items')
  
subject: Remove unused method Clipboard.empty