1 l=[foo]
   2 l=[foo, foo2]
   3 l2_size()=0
   4 Bound Integer(2) constructor: 2
   5 BiFunction with literal: unbound, 1, 2
   6 BiFunction with literal: unbound, 3, 4
   7 BiFunction with literal: unbound, 5, 6
   8 BiFunction with function: undefined, 7, 8
   9 BiFunction with function: undefined, 9, 10
  10 BiFunction with function: undefined, 11, 12