Yaml String Concatenation

[BeAllAround]

This is a Bug Report

Please, let me know if this is actually a bug or I am doing something wrong.

Thank you for your time.

Environment variables not merged and other yaml features don't seem to be there.
for example:

foo: ${foo} # Exported as env variable, this should be able to work but it treats is as normal string literal: "${foo}"
region: ${opt:region, "West Europe"} # This seems to be parsed as "optregionwesteurope"

Description

• What went wrong?
  string concatenation
• What did you expect should have happened?
  yaml should concentrate strings
• What was the config you used?
• What stack trace or error message from your provider did you see?
  No errors - just a string concatenation being ignored.

Similar or dependent issues:

• #12345

Additional Data

• Serverless Framework Version you're using: serverless-azure-functions
• Serverless CLI Version you're using: Latest
• Serverless Azure Plugin Version you're using: Latest
• Operating System: Linux
• Stack Trace: None
• Provider Error messages: None