Fuzzy call graphs
f (maybe) calls g if g.name is in f.body
This gives false positives
python call_graph.py "${ABS_PATH_OF_MODULE}" > module_callgraph.gv \
&& dot -Tpdf module_callgraph.gv -o module_callgraph.pdf \
&& open module_callgraph.pdf
(Where dot is from https://www.graphviz.org/documentation/)