let rec printInOrder tree key codeList :((char*int list)list)=
    match tree with
    |Node (value, left, right) ->
        printInOrder left (key @ [1]) codeList
        printInOrder right (key @ [0]) codeList
    |Leaf (value, symb) ->
        printfn "Symbol '%c' %A" symb key
        let codeList' = codeList @ [(symb, key)]
        if treesList.Length = codeList'.Length then codeList' else ()
    |Empty -> ()