Using pdb inside a Robot Framework file

Question

I need to set debugger from a robot file to debug and I followed the instruction on the documentation here

Evaluate    pdb.Pdb(stdout=sys.__stdout__).set_trace()    modules=sys, pdb

But when I run that robot file, I have this error:

Evaluating expression 'pdb.Pdb(stdout=sys.__stdout__).set_trace()' failed: NameError: name '__args__' is not defined nor importable as module

I am not sure what is holding this. Did anyone have this issue or any solution? Thanks so much