anchor.diff:      sign_in @user
     </pre>
   
  -  Finally OpenDSA parses RST files and fetches the names of all exercises and
  +  Finally, OpenDSA parses RST files and fetches the names of all exercises and
     shows the "<em>lti_resource</em>" layout, which opens
     "<em>views/lti/resource.html.haml</em>". The names of these exercises will be
     later shown to instructors in a tree view from where they can select
  
positive.code:       lti_instructions_opendsa_moodle_path %>.
      </p>
  
      OpenDSA implements the LTI controller and since we know that LMS expects
      Tool Provider to open in an iframe, therefore, in the start of the LTI
      controller OpenDSA allows both the launch and the resource endpoints to
      open in an iframe.<br><br>
      <pre>
        after_action :allow_iframe, only: [:launch, :resource]
  
negative.code:     def resource
        lms_instance = ensure_lms_instance()
      </pre>
      Within "<em>ensure_lms_instance</em>", OpenDSA creates a new database entry
      for this LMS instance if it does not already exist. <br><br>
      <pre>
      def ensure_lms_instance
        lms_instance = LmsInstance.find_by(url:
  