* <li>GET_SOURCE_COVER [source]: return the cover for this source</li>
* <li>SET_SOURCE_COVER [source], [luid]: set the default cover for the given
* source to the cover of the story denoted by luid</li>
* <li>GET_SOURCE_COVER [source]: return the cover for this source</li>
* <li>SET_SOURCE_COVER [source], [luid]: set the default cover for the given
* source to the cover of the story denoted by luid</li>