with open("workbook.csv") as f1:
    with open("new_workbook.csv","w") as f2:
        lines = f1.readlines()
        for line in lines:
            tab = line.split(";")
            col1 = tab[0]
            tab2 = tab[1].strip()[1:-1].split("\r")
            for value in tab2:
                f2.write(col1 + ";" + value + "\n")

    print "done."