text: var net = require('net')
  module.exports = function checkPort(fn) {
  
    var port = 5000
    var tester = net.createServer()
    .once('error', function (err) {
      if (err.code != 'EADDRINUSE') return fn(err)
      fn(null, true)
    })
    .once('listening', function() {
      tester.once('close', function() { fn(null, false) })
      .close()
    })
    .listen(port)
  }
  