DB<40>  @a = (0..4)

  DB<41>  delete @a[0,2,4]

  DB<42>  p exists $a[0]

  DB<43>  p exists $a[1]
1
  DB<44>  x @a     # shortened
0  undef
1  1
2  undef
3  3
  DB<45>  p scalar @a
4
  DB<46>