code: def create_webhook(events, url, payload_format)
        options = { :body => {
          :Events => events,
          :Url => url,
          :PayloadFormat => payload_format }.to_json }
        response = post "webhooks", options
        response.parsed_response
      end
docs: Creates a new webhook for the specified events (an array of strings).
   Valid events are "Subscribe", "Deactivate", and "Update".
   Valid payload formats are "json", and "xml".