code: def _sid_subdir_path(sid):
      
      padded_sid = format(sid, '06')
      return os.path.join(
          # subdir 1 00/XX
          padded_sid[0:2],
          # subdir 2 XX/00
          padded_sid[2:4],
          "{0}.bcolz".format(str(padded_sid))
      )
docs: Format subdir path to limit the number directories in any given
      subdirectory to 100.
  
      The number in each directory is designed to support at least 100000
      equities.
  
      Parameters
      ----------
      sid : int
          Asset identifier.
  
      Returns
      -------
      out : string
          A path for the bcolz rootdir, including subdirectory prefixes based on
          the padded string representation of the given sid.
  
          e.g. 1 is formatted as 00/00/000001.bcolz