bin/express-cli.js
function before (obj, method, fn) {
  var old = obj[method]

  obj[method] = function () {
    fn.call(this)
    old.apply(this, arguments)
  }
}
function before (obj, method, fn) {
  var old = obj[method]

  obj[method] = function () {
    fn.call(this)
    old.apply(this, arguments)
  }
}
Install a before function; AOP.