code: def _default_service_formatter(
          service_url,
          width,
          height,
          background,
          foreground,
          options
          ):
          
  
          # Build the base URL
          image_tmp = '{service_url}/{width}x{height}/{background}/{foreground}/'
          image_url = image_tmp.format(
              service_url=service_url,
              width=width,
              height=height,
              background=background,
              foreground=foreground
              )
  
          # Add any options
          if options:
              image_url += '?' + urlencode(options)
  
          return image_url
docs: Generate an image URL for a service