var key = require('./MY_SERVICE_ACCOUNT_CREDENTIALS.json')
var prediction = require('@google-cloud/prediction')({
  projectId: 'MY_PROJECT_ID',
  credentials: key
})

prediction.getModels((err, models) => {
  if (err) {
    console.log(err)
    return
  }

  console.log('Models:', models)
})

{ ApiError: Access to project denied: user requires read permissions.
    at [here goes stack trace]
  code: 401,
  errors:
   [ { domain: 'global',
       reason: 'authError',
       message: 'Access to project denied: user requires read permissions.',
       locationType: 'header',
       location: 'Authorization' } ],
  response: undefined,
  message: 'Access to project denied: user requires read permissions.' }