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* Drop Python 2 support, only Python 3.4+ is supported now.
* If ``exc_info`` is passed in, re-raise the exception (previously it would be
ignored and crash in a different way). This isn't the nicest experience,
however the behaviour is copied from ``wsgiref``\'s simple server, and most
WSGI applications implement their own exception conversion to a "500 Internal
Server Error" page already.
* Noted that the EC2 ALB to Lambda integration is also supported as it uses the
same event format as API Gateway.