gocardless/gocardless-python — pull request #5 by codeinthehole (2012-05-03 14:41:49+00:00)
Title: Added common superclass to exceptions.  

It can be useful to catch both forms of exception in some circumstances, where you don't care about which one it actually was. Plus, when you have payments going on with lots of different partners, it can be useful to determine which partner the exception came from. Having a common superclass can help.