docs: 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