docs: def description_from_content(self):
          """
          Returns the first block or sentence of the first content-like
          field.
          """
          description = ""
          # Use the first RichTextField, or TextField if none found.
          for field_type in (RichTextField, models.TextField):
              if not description:
                  for field in self._meta.fields:
                      if (isinstance(field, field_type) and
                              field.name != "description"):
                          description = getattr(self, field.name)
                          if description:
                              from yacms.core.templatetags.yacms_tags \
                                                      import richtext_filters
                              description = richtext_filters(description)
                              break
          # Fall back to the title if description couldn't be determined.
          if not description:
              description = str(self)
          # Strip everything after the first block or sentence.
          ends = ("</p>", "<br />", "<br/>", "<br>", "</ul>",
                  "\n", ". ", "! ", "? ")
          for end in ends:
              pos = description.lower().find(end)
              if pos > -1:
                  description = TagCloser(description[:pos]).html
                  break
          else:
              description = truncatewords_html(description, 100)
          try:
              description = unicode(description)
          except NameError:
              pass  # Python 3.
          return description