这个键在Google Photos相册url中的作用是什么？

const axios = require('axios');

async function generatePhotoUrl(photoId, accessToken) {
  try {
    const response = await axios.get(`https://photoslibrary.googleapis.com/v1/photos/${photoId}`, {
      headers: {
        Authorization: `Bearer ${accessToken}`
      }
    });
    const photo = response.data;
    const baseUrl = 'https://photos.google.com/share/';
    const key = photo.baseUrl.split('/').pop();
    return `${baseUrl}${key}`;
  } catch (error) {
    console.error('Error generating photo URL:', error);
    return null;
  }
}

// 示例调用
generatePhotoUrl('YOUR_PHOTO_ID', 'YOUR_ACCESS_TOKEN')
  .then(url => console.log('Generated URL:', url))
  .catch(error => console.error('Error:', error));