package Ġcollections . filter _ map Ċ Ċ import Ġcollections .* Ċ Ċ fun ĠShop . getC ities Customers Are From (): ĠSet < City > Ġ= ĊĠĠĠ Ġ/* < task Window > */ customers . map Ġ{ Ġit . city Ġ}. toSet () /* </ task Window > */ Ċ Ċ fun ĠShop . get Customers From ( city : ĠCity ): ĠList < Customer > Ġ= ĊĠĠĠ Ġ/* < task Window > */ customers . filter Ġ{ Ġit . city Ġ== Ġcity Ġ} /* </ task Window > */