code: function prepare(options) {
    return Promise.all([prepareHelpers(options), preparePartials(options)]).then(
      () => options,
      error => DrizzleError.error(error, options.debug)
    );
  }
docs: Set up templating (Handlebars).
  Register helpers and partials (partials, layouts and patterns as partials).
  
  @param {Object} options
  @return {Promise} resolves to mutated {Object} options