1 delete x? false
   2 typeof x = number
   3 delete f? true
   4 typeof f = undefined
   5 delete foo? false
   6 typeof foo = number
   7 delete func? false
   8 typeof func = function
   9 delete foo? false
  10 typeof foo? number
  11 foo = 33
  12 x in function = local
  13 delete x? = true
  14 x after delete = global
  15 x = global