Example usage::

    gst-launch spot user=<user> pass=<pass> spotifykeyfile=<keyfile> uri=spotify://spotify:track:6HFbq7cewJ7rPiffV0ciil ! autoaudiosink

Alternatively, you can set the following environment variables to avoid passing user, pass and spotifykeyfile to the gst element::

    SPOTIFY_USER=<user>
    SPOTIFY_PASS=<pass>
    SPOTIFY_APPKEY=<keyfile>

Then::

    gst-launch spot uri=spotify://spotify:track:6HFbq7cewJ7rPiffV0ciil ! autoaudiosink

Also, since the plugin implements a URI handler, this works with `playbin2`::

    gst-launch playbin2 uri=spotify://spotify:track:6HFbq7cewJ7rPiffV0ciil