old_contents: // LICENSE : MIT
  "use strict";
  // Replace key to value mapping
  // This is not for Constants.
  var exports = {
      "root": "Document",
      "paragraph": "Paragraph",
      "blockquote": "BlockQuote",
      "listItem": "ListItem",
      "list": "List",
      "Bullet": "Bullet", // no need?
      "heading": "Header",
      "code": "CodeBlock",
      "HtmlBlock": "Html",
      "ReferenceDef": "ReferenceDef",
      "horizontalRule": "HorizontalRule",
      // inline block
      'text': 'Str',
      'break': 'Break',
      'emphasis': 'Emphasis',
      'strong': 'Strong',
      'html': 'Html',
      'link': 'Link',
      'image': 'Image',
      'inlineCode': 'Code',
      'yaml': 'Yaml'
  };
  module.exports = exports;
new_contents: // LICENSE : MIT
  "use strict";
  // Replace key to value mapping
  // This is not for Constants.
  var exports = {
      "root": "Document",
      "paragraph": "Paragraph",
      "blockquote": "BlockQuote",
      "listItem": "ListItem",
      "list": "List",
      "Bullet": "Bullet", // no need?
      "heading": "Header",
      "code": "CodeBlock",
      "HtmlBlock": "Html",
      "ReferenceDef": "ReferenceDef",
      "thematicBreak": "HorizontalRule",
      // inline block
      'text': 'Str',
      'break': 'Break',
      'emphasis': 'Emphasis',
      'strong': 'Strong',
      'html': 'Html',
      'link': 'Link',
      'image': 'Image',
      'inlineCode': 'Code',
      'yaml': 'Yaml'
  };
  module.exports = exports;
subject: use thematicBreak as a map key