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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 _get_files(self):
 """ Walk the project directory for tests and returns a list. :return: list """

        excludes = [
            '.git',
            '.tox',
            '.vagrant',
            '.venv',
            os.path.basename(self._config.verifier.directory),
        ]
        generators = [
            util.os_walk(self._config.project_directory, '*.yml', excludes),
            util.os_walk(self._config.project_directory, '*.yaml', excludes),
        ]

        return [f for g in generators for f in g]