change the output directory to dest_dir
    can take a string (single file) or a list of files

def replace_directory(out_files, dest_dir):
    """
    change the output directory to dest_dir
    can take a string (single file) or a list of files

    """
    if is_sequence(out_files):
        filenames = map(os.path.basename, out_files)
        return [os.path.join(dest_dir, x) for x in filenames]
    elif is_string(out_files):
        return os.path.join(dest_dir, os.path.basename(out_files))
    else:
        raise ValueError("in_files must either be a sequence of filenames "
                         "or a string")