code: func (c *Client) GetNextPage(ctx context.Context, fullUri string, v interface{}) error {
  	// for monitor etc.
  	if strings.HasPrefix(fullUri, c.Base) {
  		fullUri = fullUri[len(c.Base):]
  	}
  	return c.MakeRequest(ctx, "GET", fullUri, nil, v)
  }
docs: // GetNextPage fetches the Page at fullUri and decodes it into v. fullUri
  // should be a next_page_uri returned in the response to a paging request, and
  // should be the full path, eg "/2010-04-01/.../Messages?Page=1&PageToken=..."