Is there a systematic way to check whether julia code is called via JuliaCall versus normal Julia?

motivation: build juliacode which has some specific behaviour when run via JuliaCall
reusing the same code simplifies the interface as well as the code size

The issue names juliacode and JuliaCall but no files, tests, or entry points. Start by locating where JuliaCall invokes the Julia code and compare that path with normal Julia execution. Done means identifying a systematic way to distinguish the two invocation modes so juliacode can reuse the same code while applying its specific behavior.

Written by the indexing model from the issue text.