Usage:
var ngram = require('simple-ngram-markov');
var options = {
length: 2, // ngram size; default is 2
stripPunctuation: true // default is true
};
var model = ngram.createModel(options);
ngram.addSentenceToModel(model, "Hey, what the heck is up man.");
ngram.addSentenceToModel(model, "Honestly I really just don't believe it. Simply.");
var sentence = ngram.generateSentence(model, 10); // 10 is the desired length of the sentence