computeDate 20041027 5 == 20041101
computeDate 20041027 (-5) == 20041022

isSubString ("otto","LottoMotto") == True
isSubString ("OTTO","LottoMotto") == False

allPermSubStrings "ot" "LottoMotto" == ["ot","to"]
allPermSubStrings "oM" "Motto" == ["Mo"]

['a','b','c']!!!4 == 'b'
['a','b','c']!!!(-4) == 'c'