def add_image(list_id, tag:nil, label:nil, custom_headers:nil)
      response = add_image_async(list_id, tag:tag, label:label, custom_headers:custom_headers).value!
      response.body unless response.nil?
    end
def add_image(list_id, tag:nil, label:nil, custom_headers:nil)
      response = add_image_async(list_id, tag:tag, label:label, custom_headers:custom_headers).value!
      response.body unless response.nil?
    end
Add an image to the list with list Id equal to list Id passed.

 @param list_id [String] List Id of the image list.
 @param tag [Integer] Tag for the image.
 @param label [String] The image label.
 @param custom_headers [Hash{String => String}] A hash of custom headers that
 will be added to the HTTP request.

 @return [Image] operation results.