fromList
  [ ( fromList [ 1 , 7 ]
    , fromList
        [ Transaction
            { transactionData = ()
            , transactionItems = fromList [ 1 , 3 , 6 , 7 ]
            }
        , Transaction
            { transactionData = ()
            , transactionItems = fromList [ 1 , 2 , 7 ]
            }
        ]
    )
  ]