The solution is to use PyObject_CallObject() instead. This function allows you to pass a single tuple of Python objects instead of the variable-length list of native C data items. The downside here is ...

Ok so technically Python is call-by-object and how it behaves depends on what you're doing. The 1st case below behaves like pass-by-value as expected.

Python’s new template strings, ... feature in Python provides a convenient way to print variables as part of a string. ... but to pass it to a function that will handle formatting duties.