earnest-blog-2-example-7.js

const config = Object.freeze({
  async: true,
  page: 4
});

const getThing = config => {
  const awesomeFunction = options => {
    const updatedOptions = Object.assign({}, options, {
      offset: options.offset || 10
    });

    // do stuff with updatedOptions  
  };
  
  return Object.freeze({
    ...config,
    awesomeFunction,
    amount: config.amount * 100
  });
};

const thing = getThing(config);