new_contents: from __future__ import absolute_import, unicode_literals
  
  from django.utils.functional import cached_property
  from wagtail.wagtailcore.blocks import ChooserBlock
  
  
  class NewsChooserBlock(ChooserBlock):
      def __init__(self, target_model, **kwargs):
          super(NewsChooserBlock, self).__init__(**kwargs)
          self.target_model = target_model
  
      @cached_property
      def widget(self):
          from wagtailnews.widgets import AdminNewsChooser
          return AdminNewsChooser(self.target_model)
  
      class Meta:
          icon = "grip"
  
subject: Add NewsChooserBlock for choosing news items in StreamFields