code: function Strategy(options, verify) {
    options = options || {};
    options.baseUrl = options.baseUrl || 'https://start.exactonline.nl';
    options.authorizationURL = options.baseUrl + '/api/oauth2/auth';
    options.tokenURL = options.baseUrl + '/api/oauth2/token';
    
    OAuth2Strategy.call(this, options, verify);
    this.name = 'exact';
    this.baseUrl = options.baseUrl;
  }
docs: `Strategy` constructor.
  
  The Exact authentication strategy authenticates requests by delegating to
  Exact using the OAuth 2.0 protocol.
  
  Applications must supply a `verify` callback which accepts an `accessToken`,
  `refreshToken` and service-specific `profile`, and then calls the `done`
  callback supplying a `user`, which should be set to `false` if the
  credentials are not valid.  If an exception occured, `err` should be set.
  
  Options:
  - `clientID`    your exact application's client id
  - `clientSecret` your exact application's client secret
  - `baseUrl`  the base Url for the Exact servers. If not specified: https://start.exactonline.nl
  - `callbackURL`    URL to which uber will redirect the user after granting authorization
  
  Examples:
  
  passport.use(new uberStrategy({
  clientID: '123-456-789',
  clientSecret: 'shhh-its-a-secret'
  baseUrl: 'https://start.exactonline.nl'
  callbackURL: 'https://www.example.net/auth/exact/callback'
  },
  function(accessToken, refreshToken, profile, done) {
  User.findOrCreate(..., function (err, user) {
  done(err, user);
  });
  }
  ));
  
  @param {Object} options
  @param {Function} verify
  @api public