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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _read_stderr(self):
 """ Reads the child process' stderr and process it. """

        output = self._decode(self._process.readAllStandardError().data())
        if self._formatter:
            self._formatter.append_message(output, output_format=OutputFormat.ErrorMessageFormat)
        else:
            self.insertPlainText(output)