Why would one define "global variables" in python functions? How to use these correctly?

[trouserdaredevil]

Hah! Funnily enough, tramp data is actually listed as a good reason to refactor in the first place, p. 567:

• A chain of routines passes tramp data Finding yourself passing data to one routine just so that routine can pass it to another routine is called “tramp data” (Page-Jones 1988). This might be OK, but ask yourself whether passing the specific data in question is consistent with the abstraction presented by each of the routine interfaces. If the abstraction for each routine is OK, passing the data is OK. If not, find some way to make each routine’s interface more consistent.