package Ġii _ collections Ċ Ċ fun ĠShop . getC ities Customers Are From (): ĠSet < City > Ġ= Ġcustomers . map Ġ{ Ġit . city Ġ}. toSet () Ċ Ċ fun ĠShop . get Customers From ( city : ĠCity ): ĠList < Customer > Ġ= Ġcustomers . filter Ġ{ Ġit . city Ġ== Ġcity Ġ} Ċ