the literal ends with 'L', and always
      unpickles to a Python long.  There doesn't seem a real purpose to the
      trailing 'L'.

      Note that LONG takes time quadratic in the number of digits when
      unpickling (this is simply due to the nature of decimal->binary
      conversion).  Proto 2 added linear-time (in C; still quadratic-time
      in Python) LONG1 and LONG4 opcodes.
      Z