def unsubscribe(self, channel_name):
if channel_name in self.channels:<EOL><INDENT>self.connection.send_event(<EOL>'<STR_LIT>', {<EOL>'<STR_LIT>': channel_name,<EOL>}<EOL>)<EOL>del self.channels[channel_name]<EOL><DEDENT>
Unsubscribe from a channel

        :param str channel_name: The name of the channel to unsubscribe from.