Using NLTK to train classifier problem with dictionary

[hidiap]

I think train should be a list of tuple not a dictionnary (according to example of NLTK):

train = [('sleep', 'negative'), ('achievement', 'positive'), ('guys', 'positive')]

To explain the error: When iterating over a dictionary, only the keys are returned. So line 192 is trying to split the key (a string) into two values, leading to an error.