How to use the vcstool.executor.USE_COLOR function in vcstool

def test_pull_api(self):
        try:
            from cStringIO import StringIO
        except ImportError:
            from io import StringIO
        from vcstool.commands.pull import main
        stdout_stderr = StringIO()

        # change and restore cwd
        cwd_bck = os.getcwd()
        os.chdir(TEST_WORKSPACE)
        try:
            # change and restore USE_COLOR flag
            from vcstool import executor
            use_color_bck = executor.USE_COLOR
            executor.USE_COLOR = False
            try:
                # change and restore os.environ
                env_bck = os.environ
                os.environ = dict(os.environ)
                os.environ.update(
                    LANG='en_US.UTF-8',
                    PYTHONPATH=(
                        os.path.dirname(os.path.dirname(__file__)) +
                        os.pathsep + os.environ.get('PYTHONPATH', '')))
                try:
                    rc = main(
                        args=['--workers', '1'],
                        stdout=stdout_stderr, stderr=stdout_stderr)
                finally:
                    os.environ = env_bck

# change and restore os.environ
                env_bck = os.environ
                os.environ = dict(os.environ)
                os.environ.update(
                    LANG='en_US.UTF-8',
                    PYTHONPATH=(
                        os.path.dirname(os.path.dirname(__file__)) +
                        os.pathsep + os.environ.get('PYTHONPATH', '')))
                try:
                    rc = main(
                        args=['--workers', '1'],
                        stdout=stdout_stderr, stderr=stdout_stderr)
                finally:
                    os.environ = env_bck
            finally:
                executor.USE_COLOR = use_color_bck
        finally:
            os.chdir(cwd_bck)

        assert rc == 1
        expected = get_expected_output('pull').decode()
        assert stdout_stderr.getvalue() == expected

def test_pull_api(self):
        try:
            from cStringIO import StringIO
        except ImportError:
            from io import StringIO
        from vcstool.commands.pull import main
        stdout_stderr = StringIO()

        # change and restore cwd
        cwd_bck = os.getcwd()
        os.chdir(TEST_WORKSPACE)
        try:
            # change and restore USE_COLOR flag
            from vcstool import executor
            use_color_bck = executor.USE_COLOR
            executor.USE_COLOR = False
            try:
                # change and restore os.environ
                env_bck = os.environ
                os.environ = dict(os.environ)
                os.environ.update(
                    LANG='en_US.UTF-8',
                    PYTHONPATH=(
                        os.path.dirname(os.path.dirname(__file__)) +
                        os.pathsep + os.environ.get('PYTHONPATH', '')))
                try:
                    rc = main(
                        args=['--workers', '1'],
                        stdout=stdout_stderr, stderr=stdout_stderr)
                finally:
                    os.environ = env_bck
            finally:

def _check_color(self, cmd):
        if not USE_COLOR:
            return
        # check if user uses colorization
        if GitClient._config_color_is_auto is None:
            _cmd = [GitClient._executable, 'config', '--get', 'color.ui']
            result = self._run_command(_cmd)
            GitClient._config_color_is_auto = result['output'] in ['', 'auto']

        # inject arguments to force colorization
        if GitClient._config_color_is_auto:
            cmd[1:1] = '-c', 'color.ui=always'

def _check_color(self, cmd):
        if not USE_COLOR:
            return
        with HgClient._config_color_lock:
            # check if user uses colorization
            if HgClient._config_color is None:
                HgClient._config_color = False
                # check if config extension is available
                _cmd = [HgClient._executable, 'config', '--help']
                result = self._run_command(_cmd)
                if result['returncode']:
                    return
                # check if color extension is available and not disabled
                _cmd = [HgClient._executable, 'config', 'extensions.color']
                result = self._run_command(_cmd)
                if result['returncode'] or result['output'].startswith('!'):
                    return
                # check if color mode is not off or not set