def save_tracks!(tracks)
      tracks_ids = tracks.map(&:id)
      url = "me/tracks"
      request_body = tracks_ids.inspect
      User.oauth_put(@id, url, request_body)
      tracks
    end
def save_tracks!(tracks)
      tracks_ids = tracks.map(&:id)
      url = "me/tracks"
      request_body = tracks_ids.inspect
      User.oauth_put(@id, url, request_body)
      tracks
    end
Save tracks to the user’s “Your Music” library.

 @param tracks [Array<Track>] The tracks to save. Maximum: 100.
 @return [Array<Track>] The tracks saved.

 @example
           tracks = RSpotify::Track.search('Know')

           user.saved_tracks.size #=> 0
           user.save_tracks!(tracks)
           user.saved_tracks.size #=> 20