def _replaceEnv(self, match):
        var = match.group('var')

        try:
            return os.environ[var]
        except KeyError:
            raise EnvironmentVariableNotFound('Can not find environment '
                                              'variable: {0}'.format(var))
Compiles a set of role prefixes
dataset/ETHPy150Open rapyuta/rce/rce-core/rce/monitor/common.py/ArgumentMixin._replaceEnv--crossover with--dataset/ETHPy150Open edelight/kitchen/kitchen/backends/lchef.py/get_role_groups