old_contents: /**
   * We'll use ES6 in our server-side code for consistency.
   * This pulls in Babel as a preprocessor for future code
   * required by Node.
   */
  require('babel/register')
  
  var Server = require('./lib/server')
  
  Server.start(process.env.PORT || 4000, function (error, server) {
    if (error) {
      throw Error(error)
    }
  
    console.log('[info] Examples listening on %s', server.info.uri)
  })
  
new_contents: /**
   * We'll use ES6 in our server-side code for consistency.
   * This pulls in Babel as a preprocessor for future code
   * required by Node.
   */
  require('babel/register')
  
  var Server = require('./lib/server')
  var assert = require('assert')
  
  Server.start(process.env.PORT || 4000, function (error, server) {
    assert.ifError(error)
  
    console.log('[info] Examples listening on %s', server.info.uri)
  })
  
subject: Use assert.ifError instead of conditional in server index