A gas is taken through the following cyclic process:
Step AB: constant-pressure expansion from A(1.0 atm, 1.0 L) to B(1.0 atm, 3.0 L)
Step BC: constant-volume rise in pressure to C(3.0 atm, 3.0 L)
Step CD: constant-pressure compression to D(3.0 atm, 1.0 L)
Step DA: constant-volume fall in pressure back to A(1.0 atm, 1.0 L)
Calculate the net work done by the gas in one complete cycle. Express your answer in joule. (Take 1 atm L ≈ 101 J.)