run python3 ___________

src/Runner_First.py -- Basic example with basic dataset (data/train.txt)
    A simple dataset with three sentences is used.
    Ngram models for these sentences are calculated. (Unigram, Bigram, Trigram, Add-one smoothing, good-turing smoothing)
    Models are tested using some unigram, bigram, trigram word units.
    New sentences are generated and perpexility score calculated.

src/Runner_Second.py -- Real dataset
    Ngram models are built using Brown corpus.
    Brown test dataset perpexility score calculated.
    New sentences are generated and perpexility score calculated.

src/Runner_Interpolation.py -- Real dataset - Interpolation
    Interplation model implemented.
    Different lambda values are testted on validation dataset. (using brute-force approach - manually selected)
    New perpexility scoring function using interpolated model is implemented.
    Finally, best lambda value is used for Brown test dataset. (perpexility)

src/Runner_Discounting_Simple.py  -- Basic example discounting
    Discounting method is implemented.
    For β = 0.5, new bigram and trigram models are calculated.
    New perpexility scoring using discounted models are implemented. (Bigram and Trigram)