def nack(self, frame):
if not frame.headers.get('<STR_LIT>'):<EOL><INDENT>raise ProtocolError("<STR_LIT>")<EOL><DEDENT>if not frame.headers.get('<STR_LIT>'):<EOL><INDENT>raise ProtocolError("<STR_LIT>")<EOL><DEDENT>
Handles the NACK command: Unacknowledges receipt of a message.
For now, this is just a placeholder to implement this version of the protocol