@cached_property<EOL><INDENT>def sentiment_assessments(self):<DEDENT>
raise NotImplementedError<EOL>
Return a tuple of form (polarity, subjectivity, assessments ) where
        polarity is a float within the range [-1.0, 1.0], subjectivity is a
        float within the range [0.0, 1.0] where 0.0 is very objective and 1.0
        is very subjective, and assessments is a list of polarity and
        subjectivity scores for the assessed tokens.

        :rtype: namedtuple of the form ``Sentiment(polarity, subjectivity, assessments)``