Problem:
 app(app(iterate(),f),x) -> app(app(cons(),x),app(app(iterate(),f),app(f,x)))

Proof:
 Containment Processor:
  loop length: 1
  terms:
   app(app(iterate(),f),x)
  context: app(app(cons(),x),[])
  substitution:
   f -> f
   x -> app(f,x)
  Qed