VERY IMPORTANT Python notes. How do you catch an exception, then re-raise it as a new exception class, but still carrying the data of the original exception? What you need is exception chaining, a feature that is only available in Python 3. For Python 2, there are a long list of caveats that achieve only in part what can be done in Python 3, and they cannot be all combined together to get the same effect.
Oh, and by the way, this was a long and hard search for me to summon all of the available information. The first Google results were clearly inadequate, and I had to try multiple different search strings.
20160812/http://nedbatchelder.com/blog/200711/rethrowing_exceptions_in_python.html
20160812/http://www.ianbicking.org/blog/2007/09/re-raising-exceptions.html
20160812/https://doughellmann.com/blog/2009/06/19/python-exception-handling-techniques/
20160812/Google python initialize a new exception object from an
existing exception
20160812/http://stackoverflow.com/questions/696047/re-raise-exception-with-a-different-type-and-message-preserving-existing-inform
20160812/https://www.python.org/dev/peps/pep-3134/
OH, and this was an interesting article linked from the Python website. Interesting because it crosses over from the same author of one of the previous very-valuable articles I’ve linked.
20160812/http://pyfound.blogspot.com/2016/08/avoiding-curse-of-knowledge-ned-batchelder.html?utm_source=feedburner&utm_medium=twitter&utm_campaign=Feed%3A+PythonSoftwareFoundationNews+%28Python+Software+Foundation+News%29