AttributeError: 'Namespace' object has no attribute 'tensor_model_parallel_size'

I am trying to run the GPT2 model on Google Colab. I have placed my training data in a loose JSON format, with one JSON containing a text sample per line. On running the preprocessing script, I am getting the above error. Kindly help me with this.

complete error below:

Opening my-corpus.json

building GPT2BPETokenizer tokenizer ...
Traceback (most recent call last):
File "/content/DeepSpeedExamples/Megatron-LM-v1.1.5-ZeRO3/tools/preprocess_data.py", line 200, in
main()
File "/content/DeepSpeedExamples/Megatron-LM-v1.1.5-ZeRO3/tools/preprocess_data.py", line 154, in main
tokenizer = build_tokenizer(args)
File "/usr/local/lib/python3.7/dist-packages/megatron/tokenizer/tokenizer.py", line 48, in build_tokenizer
args)
File "/usr/local/lib/python3.7/dist-packages/megatron/tokenizer/tokenizer.py", line 59, in _vocab_size_with_padding
args.tensor_model_parallel_size
AttributeError: 'Namespace' object has no attribute 'tensor_model_parallel_size'

Start with tools/preprocess_data.py around main() and build_tokenizer, then inspect megatron/tokenizer/tokenizer.py at _vocab_size_with_padding where the traceback occurs. Reproduce the reported GPT-2 preprocessing run in Google Colab and verify that it completes without the tensor_model_parallel_size AttributeError.