def ClassifyDataType(myList):
    intList = []
    strList = []
    scList = []
    for element in myList:
        if type(element) is int:
            intList.append(element)
        elif type(element) is str:
            if element.isalnum():
                strList.append(element)
            else:
                scList.append(element)
                
    return intList,strList,scList

def ListofDivisibleBy3(numList):
    output = []
    for element in numList:
        if element % 3 == 0:
            output.append(element)
    return output

def KeepTwoDup(numList):
    outList = []
    seen1 = []
    for element in numList:
        if (element in outList) and (element in seen1):
            continue
        elif (element in outList):
            seen1.append(element)
            outList.append(element)
        else:
            outList.append(element)
    return outList