def get_raw_files_url_dict_from_single_gist(decoded_json):
    """
    Parses the input deserialised json to obtain a dictionary of raw files urls in the GitHub Gist URL.
    :param decoded_json: A deserialised json for a single GitHub Gist from the json returned by GitHub API.
    :return: A dictionary containing key value pairs where the raw file url is the key and the file name is the value.
    """
    result = {}
    for file in decoded_json["files"]:
        file_name = decoded_json["files"][file]["filename"]
        raw_file_url = decoded_json["files"][file]["raw_url"]
        result[raw_file_url] = file_name

    return result