function cb(err, songs, result) {
        if (err) {
          return;
        }if (!songs || songs.length === 0) {
          return;
        }if (!self.player) {
          return;
        }songs.forEach(self.player.add);
      }
[Fetch songs and add them to playlist]
@param  {Object}   channel 
@param  {Object}   account 
@param  {Function}   callback
@return {Object}