How to use the pyvirtualdisplay.xauth.call function in PyVirtualDisplay

"""
        Set up the Xauthority file and the XAUTHORITY environment variable.
        """
        handle, filename = tempfile.mkstemp(
            prefix="PyVirtualDisplay.", suffix=".Xauthority"
        )
        self._xauth_filename = filename
        os.close(handle)
        # Save old environment
        self._old_xauth = {}
        self._old_xauth["AUTHFILE"] = os.getenv("AUTHFILE")
        self._old_xauth["XAUTHORITY"] = os.getenv("XAUTHORITY")

        os.environ["AUTHFILE"] = os.environ["XAUTHORITY"] = filename
        cookie = xauth.generate_mcookie()
        xauth.call("add", self.new_display_var, ".", cookie)