DB<2> use Devel::Size 'total_size'
  DB<3> total_size([map [rand, rand], 1..1000])
  DB<4> use Devel::Size 'total_size'
  DB<5> x total_size([map [rand, rand], 1..1000])
0  224176
  DB<6> x total_size([[map rand, 1..1000], [map rand, 1..1000]])
0  80464