Returns the subsentence that contains this word, otherwise the whole sentence.
        TODO

def subsentence(self):
        '''
        Returns the subsentence that contains this word, otherwise the whole sentence.
        TODO
        '''
        subsentence = []
        for word in self.sentence()[:self._position:-1]:
            # left search
            pass
        for word in self.sentence()[:self._position]:
            # right search
            pass