def METHOD_NAME(tmp_folder, instance_id, file_to_save):
    """
    Save file in given folder. The file must only be temporary saved via
    this function.
    """
    extension = "." + file_to_save.filename.split(".")[-1].lower()
    file_name = instance_id + extension.lower()
    file_path = os.path.join(tmp_folder, file_name)
    file_to_save.save(file_path)
    im = Image.open(file_path)
    if im.mode == "CMYK":
        im = im.convert("RGB")
    im.save(file_path, "PNG")
    return file_path