tracks/fsharp/exercises/custom-set/Example.fs in trackler-2.2.1.86 vs tracks/fsharp/exercises/custom-set/Example.fs in trackler-2.2.1.87

@@ -22,8 +22,10 @@
 
 let intersection left right = left.items |> List.filter (fun x -> List.contains x right.items) |> fromList
 
 let difference left right = left.items |> List.filter (fun x -> List.contains x right.items |> not) |> fromList
 
+let isEqualTo left right = (size left = size right) && (isEmpty (difference left right))
+
 let isSubsetOf left right = left.items |> List.forall (fun x -> List.contains x right.items)
 
 let isDisjointFrom left right = left.items |> List.exists (fun x -> List.contains x right.items) |> not
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