http.go
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)
}
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)
}
// 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=..."