def istring(self, in_string='<STR_LIT>'):
new_string = IString(in_string)<EOL>new_string.set_std(self.features.get('<STR_LIT>'))<EOL>if not self._casemap_set:<EOL><INDENT>self._imaps.append(new_string)<EOL><DEDENT>return new_string<EOL>
Return a string that uses this server's IRC casemapping.

        This string's equality with other strings, ``lower()``, and ``upper()`` takes this
        server's casemapping into account. This should be used for things such as nicks and
        channel names, where comparing strings using the correct casemapping can be very
        important.