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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(self):
 """ Allows changing the config on the fly """

        # TODO more efficient to read once and put watch on the file
        config = {}
        if self.config_file.exists():
            with open(self.config_file.as_posix(), 'rt') as f:  # 3.5/pypy3 can't open Path directly
                config = {k:self._override[k] if
                        k in self._override else
                        v for k, v in yaml.safe_load(f).items()}

        return config