prelude: |
  small1 = [1, 2, 3]
  small2 = [1, 2, 3, 4, 5]
  small3 = [2, 3, 4, 5]
  small4 = [2]
  big1 = [1, 2, 3, 4] * 64
  big2 = [1, 2, 3] * 64
  big3 = [1, 2] * 64

benchmark:
  small-&: small1 & small2 & small3 & small4
  small-intersection: small1.intersection(small2, small3, small4)
  big-&: big1 & big2 & big3
  big-intersection: big1.intersection(big2, big3)
