docs: function authorizationParams (options) {
    // ensure options is defined
    options = options || {}
  
    // essential request params
    var params = {
      response_type: options.response_type || 'code',
      client_id: this.client_id,
      redirect_uri: options.redirect_uri || this.redirect_uri,
      scope: options.scope || this.scope
    }
  
    // optional request params
    var optionalParameters = [
      'email',
      'password',
      'provider',
      'state',
      'response_mode',
      'nonce',
      'display',
      'prompt',
      'max_age',
      'ui_locales',
      'id_token_hint',
      'login_hint',
      'post_logout_redirect_uri',
      'acr_values'
    ]
  
    // assign optional request params
    optionalParameters.forEach(function (param) {
      if (options[param]) {
        params[param] = options[param]
      }
    })
  
    return params
  }