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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_config(self):
 """ Read credentials from the config file """

        with open(self.config_file) as cfg:
            try:
                self.config.read_file(cfg)
            except AttributeError:
                self.config.readfp(cfg)

        self.client_id = self.config.get('exist', 'client_id')
        self.client_secret = self.config.get('exist', 'client_secret')
        self.access_token = self.config.get('exist', 'access_token')