1 

     2 import CW7b._

     3 

     4 val urban_recs = 

     5   Map("1" -> List("b", "a"), 

     6       "2" -> List("y", "x"), 

     7       "3" -> List("a", "c"))

     8 

     9 val urban_names = Map("a" -> "A", "b" -> "B", "c" -> "C", "x" -> "X", "y" -> "Y")

    10 

    11 assert(most_recommended(urban_recs, urban_names).toSet ==

    12         Set(("A",2), ("B",1), ("C",1), ("X",1), ("Y",1)))

    13