Basically, but not quite. :-) The original result for b is:

  0, (1, [...]), 2, 3]

vs your version:

  [0, [...], 2, 3]

The equivalent statements to the original chained assignment are:

  a, b = 1, [0, 1, 2, 3]
  b[a] = 1, b  # relies on cpython implementation detail¹

¹: Using 1 works because the integers -5 thru 256 are interned in cpython. Otherwise, or if you don't want to rely on an implementation detail, to be truly equivalent (i.e. `id(b[1][0]) == id(a)`), it's this:

  a, b = 1, [0, 1, 2, 3]
  b[a] = a, b