Try to read data from configuration paths ($HOME/_SETTINGS_PATH,
    /etc/_SETTINGS_PATH).

def _read_from_paths():
    """
    Try to read data from configuration paths ($HOME/_SETTINGS_PATH,
    /etc/_SETTINGS_PATH).
    """
    home = os.environ.get("HOME", "/")
    home_path = os.path.join(home, _SETTINGS_PATH)
    etc_path = os.path.join("/etc", _SETTINGS_PATH)

    read_path = None
    if home and os.path.exists(home_path):
        read_path = home_path
    elif os.path.exists(etc_path):
        read_path = etc_path

    if read_path:
        with open(read_path) as f:
            _substitute_globals(
                json.loads(f.read())
            )