class_docstr: Attaches the given image to the PagerDuty request
  
  Works for both the v1 and v2 event api integrations.
  
  It is recommended to subclass this class with your own implementation of _image_url(),
  _click_url() and _alt_text() so that you can customize your own image.
code: def publish(self, alert, publication):
      publication["@pagerduty-v2.images"] = publication.get(
          "@pagerduty-v2.images", []
      )
      publication["@pagerduty-v2.images"].append(
          {
              "src": self._image_url(),
              "href": self._click_url(),
              "alt": self._alt_text(),
          }
      )
  
      publication["@pagerduty.contexts"] = publication.get(
          "@pagerduty.contexts", []
      )
      publication["@pagerduty.contexts"].append(
          {
              "type": "image",
              "src": self._image_url(),
          }
      )
  
      return publication
  
file_path: streamalert/publishers/community/pagerduty/pagerduty_layout.py
imports: from publishers.community.generic import StringifyArrays
  from streamalert.shared.publisher import AlertPublisher, Register
label_desc: Use image node_id 1 for calling the AttachImage obj's underlying member method code with example usage: obj.publish(alert, publication) and returns: publication