'Print a concordance for ``word`` with the specified context window.
Word matching is not case-sensitive.
:seealso: ``ConcordanceIndex``'

def concordance(self, word, width=79, lines=25):

    if (u'_concordance_index' not in self.__dict__):
        self._concordance_index = ConcordanceIndex(self.tokens, key=(lambda s: s.lower()))
    self._concordance_index.print_concordance(word, width, lines)
