modifying what a module defines

[Skaperen]

i have a module that defines some classes and functions. i want to also include some debug tools in it as well. my goal is to get everything in one file. but i don't want the debug tools to be defined every time the module is imported. i'd like to have a way that the code that is importing this module can indicate if it wants the debug tools, too. is there any way to do this within Python3? i'm looking for alternatives to setting (in the code doing the import) and getting (in the module) an environment variable. any suggestions?