gistfile1.txt

    list($access_token, $refresh_token, $expires) = $this->getTokens();
    $handler_stack = HandlerStack::create();
    $client = new Client([
      'auth' => 'oauth2',
      'handler' => $handler_stack,
      'base_uri' => 'https://api.smartsheet.com',
    ]);
    if ($expires < time()) {
      $form_params = [
        'grant_type' => 'refresh_token',
        AuthorizationCode::CONFIG_CLIENT_ID => static::CLIENT_ID,
        'refresh_token' => $refresh_token,
        'hash' => hash('sha256', static::CLIENT_SECRET . '|' . $refresh_token),
      ];
      $response  = $client->post(static::TOKEN_URL, ['form_params' => $form_params]);
      $tokens = json_decode($response->getBody());
      $access_token = $tokens['access_token'];
      $this->saveTokens($tokens); // Don't forget to save the tokens into the database.
    }
    $body = $client->get('/2.0/users/me', ['headers' => ['Authorization' => "Bearer $access_token"]])->getBody();