text: const fs = require('fs');
  const Convert = require('./Spec');
  
  const jsonSpec = fs.readFileSync('./bar.vl.json', 'utf-8');
  console.log('spec JSON string:', jsonSpec);
  
  const spec = Convert.toSpec(jsonSpec);
  console.log('spec Object:', spec);
  
  console.log('specToJson result', Convert.specToJson(spec));
  
  