def grains_keys_for(video_key)
      request = prepare_request :GET, {:video_key => video_key, :grains => true}.to_json
      execute_request(request).select { |key| ['images', 'videos'].include? key }
    end
def grains_keys_for(video_key)
      request = prepare_request :GET, {:video_key => video_key, :grains => true}.to_json
      execute_request(request).select { |key| ['images', 'videos'].include? key }
    end
Return the keys of the grains of a video


 @param [String] key of the desired video
 @return [Hash] response
   * "images" [String] keys to the images grains of the video
   * "files" [String] keys to the files grains of the video

 @example
   nsivideogranulate.grains_keys_for("some key")

 @raise NSIVideoGranulate::Errors::Client::SAMConnectionError when cannot connect to the SAM node
 @raise NSIVideoGranulate::Errors::Client::AuthenticationError when invalids user and/or password are provided
 @raise NSIVideoGranulate::Errors::Client::KeyNotFoundError when an invalid key is provided