Behold is a package that let's you perform contextual debugging. You can use the state inside one module to either trigger a step debugger or trigger print statements in a completely different module. Given the stateful nature of many large, multi-file applications (I'm looking at you, Django), this capability provides valuable control over your debugging work flow.
Behold is written in pure Python with no dependencies. It is compatible with both Python2 and Python3.
See the Github project page. for examples of how to use behold.