def onShowclues(self, key, subject, tokens='0'):
     """Show clues for a message - linked from the Review page."""
     tokens = bool(int(tokens)) # needs the int, as bool('0') is True
     self._writePreamble(_("Message clues"),
                         parent=('review', _('Review')))
     sourceCorpus = None
     message = None
     if self.state.unknownCorpus.get(key) is not None:
         sourceCorpus = self.state.unknownCorpus
     elif self.state.hamCorpus.get(key) is not None:
         sourceCorpus = self.state.hamCorpus
     elif self.state.spamCorpus.get(key) is not None:
         sourceCorpus = self.state.spamCorpus
     if sourceCorpus is not None:
         message = sourceCorpus.get(key).as_string()
     if message is not None:
         # For Macs?
         message = message.replace('\r\n', '\n').replace('\r', '\n')
         results = self._buildCluesTable(message, subject, tokens)
         del results.classifyAnother
         self.write(results)
     else:
         self.write(_("<p>Can't find message %r. Maybe it expired.</p>") %
                    key)
     self._writePostamble()