code: function tryPhantomjsInLib() {
    return Q.fcall(function () {
      return findValidPhantomJsBinary(path.resolve(__dirname, './lib/location.js'))
    }).then(function (binaryLocation) {
      if (binaryLocation) {
        console.log('PhantomJS is previously installed at', binaryLocation)
        exit(0)
      }
    }).fail(function () {
      // silently swallow any errors
    })
  }
docs: Check to see if the binary in lib is OK to use. If successful, exit the process.