I am inclined to drop the explicit version since you already released 4.3.* (which btw fixes a few odd bugs I was hitting with 4.0 :-)). Besides, composer can take care of this for people.
3. Open a terminal and use Composer to grab the library.
- $ composer require phpxmlrpc/phpxmlrpc:4.0
+ $ composer require phpxmlrpc/phpxmlrpc:4
4. Write your code.
Once Composer has downloaded the component(s), all you need to do is include the vendor/autoload.php file that