divided code into more cells; added sees to train_test_split;

[kamil-kaczmarek]

Changes summary

Fixes To NLP module

PR scope

• [ ] new notebook
• [x] improvements to the existing notebook
• [ ] bug fixes
• [x] other

Checklist

• [x] notebook is without outputs
• [X] empty cells are removed
• [x] code is formatted with black
• [x] imports are sorted
• [ ] if new notebook is added, README is updated