Negation Handling NLTK and adding Neutral

i am working on a sentiment analysis (python) and i got to a point were i need to handle negation but i didn't know how to do that i just figured out a method how to do it but still not working right + i am working with 7 classifiers including (naive bayes, SVC, LinearSVC, NuSVC / MultinomialNB, BeoulliNB, LogisticRegression, SGDClassifier) and a vote classifier (that take all the classifier using the mode) to determine the final polarity if positive or negative; it's really basic code for you to understand so i just need to include negation handling and to give "pos, neg and neutral" and the "subjectivity" right now just giving me "pos" and "neg"; please need some help anything will be very kind from u thanks in advance. If you want me to include my code please ask me i can provide it thanks.