def change_header__generator(csvfile, header1, header2=None):
    """
    Replace a csv header row with a new one (or two).

    Skip the first row of the input csv file;
    in its place, yield one (or two) new header(s),
    and then yield the remainder of the input file.
    """
    yield header1
    if header2:
        yield header2
    next(csvfile)
    for row in csvfile:
        yield row
