ClearAll[ImportAll];
ImportAll[lang_String] :=
  Module[{data = {}, continue = True, cmcontinue = "", xml},
   While[continue,
    xml = Import[
      "http://www.rosettacode.org/w/api.php?action=query&list=categorymembers&cmtitle=Category:" <>
      lang <>
      "&cmlimit=500&format=xml&cmcontinue=" <>
      cmcontinue,
      "XML"];
    AppendTo[data, Cases[xml, XMLElement["cm", _, {}], Infinity]];
    cmcontinue = Cases[xml, XMLElement["continue", cmcontinue_, {}] :> cmcontinue, Infinity];
    If[Length[cmcontinue] > 0,
     cmcontinue = Last@First@First@cmcontinue;,(*else*)
     cmcontinue = "";];
    continue = (cmcontinue != "");];
   Return[Cases[data, HoldPattern["title" -> x_] :> x, Infinity]];];

unimplementedTasks =
  Complement[ImportAll["Programming_Tasks"], ImportAll["Mathematica"]]