bookmark/get - Returns a single existing bookmark.id - The ID of the bookmark to get.{id: <number> - The ID of the bookmark.url: <string> - The URL of the bookmark.title: <string> - The title of the bookmark.tags: <string> - The space-separated list of tags.insert_time: <number> - The Unix timestamp of when the bookmark was created.update_time: <number> - The Unix timestamp of when the bookmark was last modified.}BOOKMARK_NOT_FOUND - A bookmark with the ID doesn't exist.