code: def sentiment(self):
          
          #: Enhancement Issue #2
          #: adapted from 'textblob.en.sentiments.py'
          #: Return type declaration
          _RETURN_TYPE = namedtuple('Sentiment', ['polarity', 'subjectivity'])
          _polarity = 0
          _subjectivity = 0
          for s in self.sentences:
              _polarity += s.polarity
              _subjectivity += s.subjectivity
          try:
              polarity = _polarity / len(self.sentences)
          except ZeroDivisionError:
              polarity = 0.0
          try:
              subjectivity = _subjectivity / len(self.sentences)
          except ZeroDivisionError:
              subjectivity = 0.0
          return _RETURN_TYPE(polarity, subjectivity)
docs: Return a tuple of form (polarity, subjectivity ) where polarity
          is a float within the range [-1.0, 1.0] and subjectivity is a float
          within the range [0.0, 1.0] where 0.0 is very objective and 1.0 is
          very subjective.
  
          :rtype: named tuple of the form ``Sentiment(polarity=0.0, subjectivity=0.0)``