code: def process(self, diagnostic):
          
          diagnostic.notes += self._appended_notes
          self.render_diagnostic(diagnostic)
          if diagnostic.level == "fatal" or \
                  (self.all_errors_are_fatal and diagnostic.level == "error"):
              raise Error(diagnostic)
docs: The default implementation of :meth:`process` renders non-fatal
          diagnostics to ``sys.stderr``, and raises fatal ones as a :class:`Error`.