RosettaCodeData/Task/Null-object/OoRexx/null-object-2.rexx

a=.array~of('A','B')
  i=3
  if a[i] == .nil then say "Item" i "of array A is missing"
  if \var("INPUT") then say "Variable INPUT is not assigned"
  if \var("var") then say "Variable" var "is not assigned"