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.

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)