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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 config_file(self, filename):
 """Load configuration data from provided file and inject values into sys.argv. Args: config (str):
 The configuration file name. """

        if os.path.isfile(filename):
            with open(filename, 'r') as fh:
                self._config_data = json.load(fh)
        else:
            self.tcex.log.error('Could not load configuration file "{}".'.format(filename))