What is "get_descendants_of"? How can i solve this?

[clarkej]

Maybe a circular reference or import case as nabin notes

ImportError: Module import failed for Tax Rule (erpnext.accounts.doctype.tax_rule.tax_rule)

Have you modified the code of tax_rule.py? Sometime module import fails due to wrong import statement/ circular import inside py file.

Python Circular Imports

Too bad I am not informed how to analyse and resolve this - IMHO one misfortune of untyped languages like Python!