Associative array with an indexed array

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Вопрос простой

var masterTaskList:Object = new Object();
masterTaskList["Monday"] = ["wash dishes", "take out trash"];
masterTaskList["Tuesday"] = ["wash dishes", "pay bills"];
masterTaskList["Wednesday"] = ["wash dishes", "dentist", "wash dog"];
masterTaskList["Thursday"] = ["wash dishes"];
masterTaskList["Friday"] = ["wash dishes", "clean house"];
masterTaskList["Saturday"] = ["wash dishes", "wash car", "pay rent"];
masterTaskList["Sunday"] = ["mow lawn", "fix chair"];

trace(masterTaskList.Wednesday[1]); // output: dentist
trace(masterTaskList.Sunday[0]);    // output: mow lawn

var mykey:String;
mykey="Wednesday";

trace(masterTaskList.mykey[0]); // естественно ошибка! 
trace(masterTaskList.[mykey][0]); // естественно ошибка!

Как правильно узнать значение masterTaskList.[mykey][0] ?

[etc]

trace(masterTaskList[mykey][0])

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__etc
спасибо, работает