text: // Example usage:
  // node screenshot.js http://google.com 1400 800
  
  var Nightmare = require('nightmare');
  var nightmare = Nightmare();
  
  var url = process.argv[2];
  var width = process.argv[3] || 1400;
  var height = process.argv[4] || 860;
  var delayInMs = process.argv[5] || 10000;
  
  var formattedDate = new Date().toISOString().replace(/:/g, '-');
  var path = './png/' + formattedDate + '.png';
  
  nightmare
    .goto(url)
    .viewport(width, height)
    .wait(delayInMs)
    .screenshot(path)
    .end()
    .then(function () {
      console.log('Saved screenshot to ' + path);
    });
  