add another validator

examples/acceptance_tests/077/validators/spend2.ak

@@ -0,0 +1,15 @@
+use aiken/list
+use aiken/transaction.{Output, ScriptContext}
+
+validator backtrace {
+  fn(_datum: Void, _redeemer: Void, context: ScriptContext) -> Bool {
+    expect Some(_) = list.find(context.transaction.outputs, fn(_) { True })
+    let _ = find_stuff(context)
+    True
+  }
+}
+
+fn find_stuff(context) -> Output {
+  expect Some(stuff) = list.find(context.transaction.outputs, fn(_) { True })
+  stuff
+}