def month_year(dte):
    """
    Return a string in the format MM-YYYY where MM is the month of the dte and YYYY is the year of the dte.
    If the month is less than 10, MM is a single digit.

    Argument:
        dte - the dte to use in making the string
    """
    result = str(dte.month) + "-" + str(dte.year)
    return result