Billing code sample function change (#1905)
Billing code sample function change (#1905)

* Update index.js

Updating sample code based on Node 10 runtime environment variable changes: https://cloud.google.com/functions/docs/env-var#environment_variables_set_automatically

* Billing function fixes for reviews and testing

* Simplify environment variable code

Co-authored-by: Ace Nassri <66a75941ededf131c26806c52c2b5e1fb48aad03@google.com>
Co-authored-by: F. Hinkelmann <bfca2660d8321d14063d908366d26ce6f4981952@gmail.com>
GoogleCloudPlatform/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples