code: def build(attrs)
        playlist = Playlist.new(client, attrs)
  
        # Update existing in cache or cache a new playlist
        if existing = @playlists[playlist.id]
          playlist = existing
          playlist.attributes = attrs
        else
          @playlists[playlist.id] = playlist
        end
  
        playlist
      end
docs: Gets the playlist represented by the given attributes.
  
   If the playlist hasn't been previously accessed, then a new Playlist
   instance will get created.
  
   @api private
   @param [Hash] attrs The attributes representing the playlist
   @return [Turntabler::Playlist]