docs: def format_size(size, threshold=1536):
      """Return file size as string from byte size.
  
      >>> format_size(1234)
      '1234 B'
      >>> format_size(12345678901)
      '11.50 GiB'
  
      """
      if size < threshold:
          return "%i B" % size
      for unit in ('KiB', 'MiB', 'GiB', 'TiB', 'PiB'):
          size /= 1024.0
          if size < threshold:
              return "%.2f %s" % (size, unit)
      return 'ginormous'