[lec04] Do not throw compile errors in repo state

src/main/scala/laziness/Stream.scala

 package laziness
 
 sealed trait Stream[+A] {
-  import Stream._
+  // uncomment to be able to use cons(h, t) and empty directly
+  // imports methods from the companion object
+  //import Stream._
 
   def toList: List[A] = ???