text = """Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam ornare
tempor lacus, quis pellentesque diam tempus vitae. Morbi justo mauris,
congue sit amet imperdiet ipsum dolor sit amet, consectetur adipiscing elit. Nullam ornare
tempor lacus, quis pellentesque diam"""
tokens = nltk.word_tokenize(text)
What are ngram counts and how to implement using nltk?