code: def text_filter(regex_base, value):
      
      from thumbnails import get_thumbnail
      regex = regex_base % {
          'caption': '[a-zA-Z0-9\.\,:;/_ \(\)\-\!\?\"]+',
          'image': '[a-zA-Z0-9\.:/_\-\% ]+'
      }
      images = re.findall(regex, value)
  
      for i in images:
          image_url = i[1]
          image = get_thumbnail(
              image_url,
              **settings.THUMBNAIL_FILTER_OPTIONS
          )
          value = value.replace(i[1], image.url)
  
      return value
docs: A text-filter helper, used in ``markdown_thumbnails``-filter and ``html_thumbnails``-filter.
      It can be used to build custom thumbnail text-filters.
  
      :param regex_base: A string with a regex that contains ``%(captions)s`` and ``%(image)s`` where
                         the caption and image should be.
      :param value: String of text in which the source URLs can be found.
      :return: A string ready to be put in a template.