Recent flake8 complains about a missing space after keywords:

• C-style while(condition) instead of while condition:
• not(condition) (actually better: return self.version is not None and self.operator is not None, but that's personal preference)
• Rewrote the if-condition checking for stream attr to remove the or
• Missing error class in raise. Settled on ValueError as the hdlr has a missing or invalid stream value