Issue

Issue #20: Exception: Callable has no attribute __abc_registry

What

Users receive a Callable has no attribute __abc_registry error.

This is a known issue when installing typing on a system that has Python >= 3.7. It will result in an error.

Test

1. Installed the latest available version of the SDK through pip so it will install all required dependencies too.
2. Create a test.py file and import the Cybersource SDK in an environment with Python >= 3.7.
3. Execute the script python or upload the code to Lambda and run it. It should no longer fail.