.'
        auth header.

    :param proxy_basic_auth:
        Colon-separated username:password string for 'proxy-authorization: basic ...'
        auth header.

    :param disable_cache:
        If ``True``, adds 'cache-control: no-cache' header.

    Example::

        >>> make_headers(keep_alive=True, user_agent="Batman/1.0")
        {'connection': 'keep-alive', 'user-agent': 'Batman/1.0'}
        >>> make_headers(accept_encoding=True)
        {'accept-encoding': 'gzip,deflate'}
    ú