Function Name: site_image_url
Description: Get the image URL the site uses
Parameters:
- sid: Optional.The site id for which we want to find out the image.
- url: Optional. The url for which site we want to find out the image, in case that sid was not specified. One of this parameters must be specified.
Return:
- status: The status of the result, 0 for OK, 1 for error (look at the error code and messages)
- url: The image URL for the site.