message: Parse once and re-use the parsed output
  Rather than re-parsing the same output in each function
diff: @@ -24,7 +24,10 @@ import commonmark from 'commonmark';
  export default class Markdown {
  constructor(input) {
  this.input = input;
  - this.parser = new commonmark.Parser();
  +
  + const parser = new commonmark.Parser();
  + this.parsed = parser.parse(this.input);
  +
  this.renderer = new commonmark.HtmlRenderer({safe: false});
  }
  @@ -49,8 +52,7 @@ export default class Markdown {
  dummy_renderer.softbreak = function(t) { return t; };
  dummy_renderer.paragraph = function(t) { return t; };
  - const dummy_parser = new commonmark.Parser();
  - dummy_renderer.render(dummy_parser.parse(this.input));
  + dummy_renderer.render(this.parsed);
  return is_plain;
  }
  @@ -73,8 +75,7 @@ export default class Markdown {
  }
  };
  - var parsed = this.parser.parse(this.input);
  - var rendered = this.renderer.render(parsed);
  + var rendered = this.renderer.render(this.parsed);
  this.renderer.paragraph = real_paragraph;
  @@ -116,8 +117,7 @@ export default class Markdown {
  }
  };
  - var parsed = this.parser.parse(this.input);
  - var rendered = this.renderer.render(parsed);
  + var rendered = this.renderer.render(this.parsed);
  this.renderer.paragraph = real_paragraph;
  