I am not able to understand how to get the top_k_indices after performing the BM25_RETRIEVER.retrieve( None, k = None) step.
I think this has been addressed in the ungraded lab. Kindly check it out. Or you can check the documentation. You could check here for examples in the documentation.
Hey @sumanta13 were you able to get this working? The code for this exercise has just been updated & fixed on Coursera, refreshing your workspace should give you access to the fixed copy of the notebook. Let me know if that solves your issue.