text: var Bugsnag = require('@bugsnag/node')
  Bugsnag.start({
    apiKey: process.env.BUGSNAG_API_KEY,
    endpoints: {
      notify: process.env.BUGSNAG_NOTIFY_ENDPOINT,
      sessions: process.env.BUGSNAG_SESSIONS_ENDPOINT
    }
  })
  
  //
  function add (a) {
    return function (b) {
      return a + b
    }
  }
  
  add(5)(2) // -> 7
  subtract(5)(2) // -> 3
  
  Bugsnag.notify(new Error('surround me'))
  
  function subtract (a) {
    return function (b) {
      return add(a)(-b)
    }
  }
  