code: function parseBook(book) {
      return timing.measure(
          'parse.book',
          Promise(book)
          .then(parseIgnore)
          .then(parseConfig)
          .then(parseLanguages)
          .then(function(resultBook) {
              if (resultBook.isMultilingual()) {
                  return parseMultilingualBook(resultBook);
              } else {
                  return parseBookContent(resultBook);
              }
          })
      );
  }
docs: Parse a whole book from a filesystem
  
  @param {Book} book
  @return {Promise<Book>}