docs: def _calc_thumb_filename(self, thumb_name):
          """
          Calculates the correct filename for a would-be (or potentially
          existing) thumbnail of the given size.
          
          NOTE: This includes the path leading up to the thumbnail. IE:
          uploads/cbid_images/photo.png
          
          size: (tuple) In the format of (width, height)
          
          Returns a string filename.
          """
          filename_split = self.name.rsplit('.', 1)
          file_name = filename_split[0]
          file_extension = self.get_thumbnail_format()
  
          return '%s_%s.%s' % (file_name, thumb_name, file_extension)