Document function declaration

[janrito]

Trying to declare a couple of helper functions. But at the moment, it is a bit of a trial and error process because of the lack of documentation. I have questions such as:

• How do I declare parameters?
• How do I return values? echo? exit?
• How do I print to stdout/stderr from a function?

AS an example, I'm trying to create a function that tests whether I am in a local "minikube" or CI environment before running a specialised testing pipeline. I want to abstract that test to a function, because I have a couple of such testing pipelines. I want the function to print an error, and then stop the pipeline early. Can I exit from inside a function, or do I have to return a value and test for it in the pipeline to exit.