old_contents: from django import forms
  from django.forms.util import flatatt
  from django.template.loader import render_to_string
  from django.utils.encoding import force_text
  from django.utils.safestring import mark_safe
  
  
  class RichTextEditorWidget(forms.Textarea):
      class Media:
          js = ('admin/js/ckeditor/ckeditor.js',
                'admin/js/ckeditor/jquery-ckeditor.js')
  
      def render(self, name, value, attrs={}):
          if value is None:
              value = ''
          final_attrs = self.build_attrs(attrs, name=name)
          return mark_safe(render_to_string('ckeditor/widget.html', {
              'final_attrs': flatatt(final_attrs),
              'value': force_text(value),
              'id': final_attrs['id'],
          }))
  
new_contents: from django import forms
  
  from django.template.loader import render_to_string
  from django.utils.encoding import force_text
  from django.utils.safestring import mark_safe
  
  try:
      from django.forms.utils import flatatt
  except ImportError:
      from django.forms.util import flatatt
  
  
  class RichTextEditorWidget(forms.Textarea):
      class Media:
          js = ('admin/js/ckeditor/ckeditor.js',
                'admin/js/ckeditor/jquery-ckeditor.js')
  
      def render(self, name, value, attrs={}):
          if value is None:
              value = ''
          final_attrs = self.build_attrs(attrs, name=name)
          return mark_safe(render_to_string('ckeditor/widget.html', {
              'final_attrs': flatatt(final_attrs),
              'value': force_text(value),
              'id': final_attrs['id'],
          }))
  
subject: Fix flatatt import path for Django 1.9