def add_tracks!(tracks, position: nil)
      track_uris = nil
      if tracks.first.is_a? String
        track_uris = tracks.join(',')
      else
        track_uris = tracks.map(&:uri).join(',')
      end
      url = "#{@path}/tracks?uris=#{track_uris}"
      url << "&position=#{position}" if position

      response = User.oauth_post(@owner.id, url, {}.to_json)
      @total += tracks.size
      @tracks_cache = nil

      if RSpotify::raw_response
        @snapshot_id = JSON.parse(response)['snapshot_id']
        return response
      end

      @snapshot_id = response['snapshot_id']
      tracks
    end
def add_tracks!(tracks, position: nil)
      track_uris = nil
      if tracks.first.is_a? String
        track_uris = tracks.join(',')
      else
        track_uris = tracks.map(&:uri).join(',')
      end
      url = "#{@path}/tracks?uris=#{track_uris}"
      url << "&position=#{position}" if position

      response = User.oauth_post(@owner.id, url, {}.to_json)
      @total += tracks.size
      @tracks_cache = nil

      if RSpotify::raw_response
        @snapshot_id = JSON.parse(response)['snapshot_id']
        return response
      end

      @snapshot_id = response['snapshot_id']
      tracks
    end
Adds one or more tracks to a playlist in user's Spotify account. This method is only available when the
 current user has granted access to the *playlist-modify-public* and *playlist-modify-private* scopes.

 @param tracks [Array<Track>, Array<String>] Tracks to be added. Either array of Tracks or strings where each string is a valid spotify track uri. Maximum: 100 per request
 @param position [Integer, NilClass] The position to insert the tracks, a zero-based index. Default: tracks are appended to the playlist
 @return [Array<Track>] The tracks added

 @example
           tracks = RSpotify::Track.search('Know', 30)
           playlist = user.create_playlist!('my-awesome-playlist')

           playlist.add_tracks!(tracks)
           playlist.tracks.size       #=> 30
           playlist.tracks.first.name #=> "Somebody That I Used To Know"

           playlist.add_tracks!(tracks, position: 20)
           playlist.tracks[20].name #=> "Somebody That I Used To Know"