title: How to insert a comment line to YAML in Python using ruamel.yaml?
body: <p>I have a structure like this to which I want to add comment lines using <code>ruamel.yaml</code>:</p>
  
  <pre><code>xyz:
    a: 1    # comment 1
    b: 2
  
  test1:
    test2:
      test3: 3
  </code></pre>
  
  <p>Now, I want to insert comment-lines (not eol_comments) to make it look like this:</p>
  
  <pre><code>xyz:
    a: 1    # comment 1
    b: 2
  
  # before test1 (top level)
  test1:
    # before test2
    test2:
      # after test2
      test3: 3
  </code></pre>
  
  <p>I know, that I can add eol_comments using <code>ruamel.yaml</code>, but I didn't find a way to add whole comment lines.</p>