docs: function hashDocument(document) {
    var words;
  
    if (Buffer.isBuffer(document)) {
      words = Base64.parse(document.toString('base64'));
    } else if (typeof document === 'string') {
      words = Base64.parse(document);
    } else {
      throw new TypeError('Expected document to be Buffer or String');
    }
  
    var hash = sha256(words);
  
    return hash.toString(Hex);
  }