def get_join_parameters(join_kwargs):
    """
    Convenience function to determine the columns to join the right and
    left DataFrames on, as well as any suffixes for the columns.
    """
    by = join_kwargs.get('by', None)
    suffixes = join_kwargs.get('suffixes', ('_x', '_y'))
    if by is None:
        left_on, right_on = None, None
    elif isinstance(by, str):
        left_on, right_on = by, by
    elif not isinstance(by[0], str):
        left_on = by[0]
        right_in = by[1]
    else:
        left_on, right_on = by, by
    return left_on, right_on, suffixes
