HTTPRequest class doesn't exist in PHP 7+ (replacement in documentation)

Problem: 

HTTPRequest class doesn't exist in PHP 7+

The HTTP extension is a PECL package that needs to be installed separately.

This is 'difficult to impossible' to accomplish on shared hosting platforms

$request = new HttpRequest();

However, the https://v3.developer.constantcontact.com/ guide consistently uses HttpRequest() as the example.

Requested Solution:

Test, confirm and show real world working examples using cURL instead.