code: public function authURL($state)
      {
          $url = $this->settings['authentication_url'];
  
          $params = [
              'client_id' => $this->settings('api_key'),
              'redirect_uri' => $this->settings('redirect_uri'),
              'scope' => $this->settings('permissions'),
              'state' => $state,
          ];
  
          return $url.'?'.http_build_query($params);
      }
docs: Returns the authentication
  URL to which we should be
  redirecting to.
  
  
  @return string