code: function preview(name, content) {
    console.log('=======');
    console.log('JSON SCHEMA PREVIEW BEGIN: ' + name);
    console.log('=======');
    console.log(JSON.stringify(content, null, 2));
    console.log('=======');
    console.log('JSON SCHEMA PREVIEW END: ' + name);
    return Promise.resolve();
  }
docs: Write the generated schema to the console as pretty-json output.  This is
  useful for debugging purposes