docs: def translate(self, exc):
          """Return translation of exception to new class.
  
          Calling code should only raise exception if exception class is passed
          in, else ``None`` (which signifies no wrapping should be done).
          """
          # Find actual class.
          for key in self.translations.keys():
              if isinstance(exc, key):
                  # pylint: disable=unsubscriptable-object
                  return self.translations[key](str(exc))
  
          return None