old_contents: 
  from django.db import models
  from django.utils.translation import ugettext_lazy as _
  
  from mezzanine.conf import settings
  from mezzanine.core.fields import FileField
  from mezzanine.core.models import Displayable, Ownable, RichText, Slugged
  from mezzanine.generic.fields import CommentsField, RatingField
  
  
  class BlogPost(Displayable, Ownable, RichText):
      """
      A blog post.
      """
  
      categories = models.ManyToManyField("BlogCategory", blank=True,
                                          related_name="blogposts")
      allow_comments = models.BooleanField(default=True)
      comments = CommentsField(verbose_name=_("Comments"))
      rating = RatingField(verbose_name=_("Rating"))
      featured_image = FileField(verbose_name=_("Featured Image"), null=True,
                                 upload_to="blog", max_length=255, blank=True)
  
      class Meta:
          verbose_name = _("Blog post")
          verbose_name_plural = _("Blog posts")
          ordering = ("-publish_date",)
  
      @models.permalink
      def get_absolute_url(self):
          url_name = "blog_post_detail"
          kwargs = {"slug": self.slug}
          if settings.BLOG_URLS_USE_DATE:
              url_name = "blog_post_detail_date"
              month = str(self.publish_date.month)
              if len(month) == 1:
                  month = "0" + month
              kwargs.update({"month": month, "year": self.publish_date.year})
          return (url_name, (), kwargs)
  
  
  class BlogCategory(Slugged):
      """
      A category for grouping blog posts into a series.
      """
  
      class Meta:
          verbose_name = _("Blog Category")
          verbose_name_plural = _("Blog Categories")
  
      @models.permalink
      def get_absolute_url(self):
          return ("blog_post_list_category", (), {"slug": self.slug})
  
new_contents: 
  from django.db import models
  from django.utils.translation import ugettext_lazy as _
  
  from mezzanine.conf import settings
  from mezzanine.core.fields import FileField
  from mezzanine.core.models import Displayable, Ownable, RichText, Slugged
  from mezzanine.generic.fields import CommentsField, RatingField
  
  
  class BlogPost(Displayable, Ownable, RichText):
      """
      A blog post.
      """
  
      categories = models.ManyToManyField("BlogCategory",
                                          verbose_name=_("Categories"),
                                          blank=True, related_name="blogposts")
      allow_comments = models.BooleanField(verbose_name=_("Allow comments"),
                                           default=True)
      comments = CommentsField(verbose_name=_("Comments"))
      rating = RatingField(verbose_name=_("Rating"))
      featured_image = FileField(verbose_name=_("Featured Image"), null=True,
                                 upload_to="blog", max_length=255, blank=True)
  
      class Meta:
          verbose_name = _("Blog post")
          verbose_name_plural = _("Blog posts")
          ordering = ("-publish_date",)
  
      @models.permalink
      def get_absolute_url(self):
          url_name = "blog_post_detail"
          kwargs = {"slug": self.slug}
          if settings.BLOG_URLS_USE_DATE:
              url_name = "blog_post_detail_date"
              month = str(self.publish_date.month)
              if len(month) == 1:
                  month = "0" + month
              kwargs.update({"month": month, "year": self.publish_date.year})
          return (url_name, (), kwargs)
  
  
  class BlogCategory(Slugged):
      """
      A category for grouping blog posts into a series.
      """
  
      class Meta:
          verbose_name = _("Blog Category")
          verbose_name_plural = _("Blog Categories")
  
      @models.permalink
      def get_absolute_url(self):
          return ("blog_post_list_category", (), {"slug": self.slug})
  
subject: add some verbose names for blog