Method __contains__

tools/python-3.11.9-amd64/Lib/mailbox.py:408–411

Return True if the keyed message exists, False otherwise.

(self, key)

            yield key

    def __contains__(self, key):
        """Return True if the keyed message exists, False otherwise."""
        self._refresh()
        return key in self._toc

    def __len__(self):
        """Return a count of messages in the mailbox."""