Flatten structure of exceptions dictionary.

def _flatten_ex_dict(self):
        """Flatten structure of exceptions dictionary."""
        odict = {}
        for _, fdict in self._ex_dict.items():
            for (extype, exmsg), value in fdict.items():
                key = value["name"]
                odict[key] = copy.deepcopy(value)
                del odict[key]["name"]
                odict[key]["type"] = extype
                odict[key]["msg"] = exmsg
        return odict