code: function getBitbucketId (text) {
    text = 'markdown-header-' + text
      .toLowerCase()
      .replace(/\\(.)/g, (_m, c) => c.charCodeAt(0)) // add escaped chars with their charcode
      .normalize('NFKD').replace(/[\u0300-\u036f]/g, '')
      .replace(/[^\w\s-]/g, '')
      .replace(/\s+/g, '-')     // whitespace
      .replace(/-+/g, '-')      // duplicated hyphen
      .replace(/^-+|-+$/g, '')  // heading/ tailing hyphen
    return text
  }
docs: getBitbucketId - anchors used at bitbucket.org
  @private
  @see: https://github.com/Python-Markdown/markdown/blob/master/markdown/extensions/toc.py#L25
  There seams to be some "magic" preprocessor which could not be handled here.
  @see: https://github.com/Python-Markdown/markdown/issues/222
  If no repetition, or if the repetition is 0 then ignore. Otherwise append '_' and the number.
  https://groups.google.com/d/msg/bitbucket-users/XnEWbbzs5wU/Fat0UdIecZkJ