title: Read REF type node of a OpenCV generated YML file
body: <p>I tried to read node in a YML file. There I checked node type. Which is 4. According to the <a href="https://docs.opencv.org/3.4/de/dd9/classcv_1_1FileNode.html#aeac30395ae3473911171a2091c6ab74c" rel="nofollow noreferrer">type chart</a>, It maps into The <code>REF</code> type. I referred this <a href="https://docs.opencv.org/master/dd/d74/tutorial_file_input_output_with_xml_yml.html" rel="nofollow noreferrer">doc</a>,   Under that I haven't seen way to read data of <code>REF</code> type node . Any help is appreciated to read my node. Thank you.</p>
  <pre><code>import cv2
  fs = cv2.FileStorage(&quot;ProjectorParameters.yml&quot;, cv2.FILE_STORAGE_READ)
  fn = fs.getNode(&quot;FeaturesValue&quot;)
  print (fn.type ()) # 4 
  print (fn.isSeq ()) # True
  </code></pre>
  <p>The yml file that I wanna read.</p>
  <pre><code>%YAML:1.0
  ---
  zThreshold: 40.
  FeaturesValue: [ 13, 15, 25, 7, 27, 19, 31, 23, 29, 31, 13, 15, 25, 7 ]
  </code></pre>