How to use the localstack.utils.common.save_file function in localstack

def test_get_java_lib_folder_classpath(self):
        jar_file = os.path.join(new_tmp_dir(), 'foo.jar')
        save_file(jar_file, '')
        self.assertEquals('.:foo.jar', lambda_executors.Util.get_java_classpath(jar_file))

def get_or_create_file(config_file):
    if os.path.exists(config_file):
        return config_file
    try:
        save_file(config_file, '{}')
        return config_file
    except Exception:
        pass

dynamodb_url = DYNAMODB_JAR_URL_ALPINE if in_docker() else DYNAMODB_JAR_URL
        download_and_extract_with_retry(dynamodb_url, tmp_archive, INSTALL_DIR_DDB)

    # fix for Alpine, otherwise DynamoDBLocal fails with:
    # DynamoDBLocal_lib/libsqlite4java-linux-amd64.so: __memcpy_chk: symbol not found
    if is_alpine():
        ddb_libs_dir = '%s/DynamoDBLocal_lib' % INSTALL_DIR_DDB
        patched_marker = '%s/alpine_fix_applied' % ddb_libs_dir
        if APPLY_DDB_ALPINE_FIX and not os.path.exists(patched_marker):
            patched_lib = ('https://rawgit.com/bhuisgen/docker-alpine/master/alpine-dynamodb/' +
                'rootfs/usr/local/dynamodb/DynamoDBLocal_lib/libsqlite4java-linux-amd64.so')
            patched_jar = ('https://rawgit.com/bhuisgen/docker-alpine/master/alpine-dynamodb/' +
                'rootfs/usr/local/dynamodb/DynamoDBLocal_lib/sqlite4java.jar')
            run("curl -L -o %s/libsqlite4java-linux-amd64.so '%s'" % (ddb_libs_dir, patched_lib))
            run("curl -L -o %s/sqlite4java.jar '%s'" % (ddb_libs_dir, patched_jar))
            save_file(patched_marker, '')

    # fix logging configuration for DynamoDBLocal
    log4j2_config = """
      
        
          
        
      
      
        
      
    """
    log4j2_file = os.path.join(INSTALL_DIR_DDB, 'log4j2.xml')
    save_file(log4j2_file, log4j2_config)
    run('cd "%s" && zip -u DynamoDBLocal.jar log4j2.xml || true' % INSTALL_DIR_DDB)

def log(self, s):
        s = '%s\n' % s
        if self.log_file:
            save_file(self.log_file, s, append=True)

run("curl -L -o %s/sqlite4java.jar '%s'" % (ddb_libs_dir, patched_jar))
            save_file(patched_marker, '')

    # fix logging configuration for DynamoDBLocal
    log4j2_config = """
      
        
          
        
      
      
        
      
    """
    log4j2_file = os.path.join(INSTALL_DIR_DDB, 'log4j2.xml')
    save_file(log4j2_file, log4j2_config)
    run('cd "%s" && zip -u DynamoDBLocal.jar log4j2.xml || true' % INSTALL_DIR_DDB)

node-address {
        protocol = http
        host = "%s"
        port = %s
        context-path = ""
    }
    rest-sqs {
        enabled = true
        bind-port = %s
        bind-hostname = "0.0.0.0"
        sqs-limits = strict
    }
    """ % (LOCALSTACK_HOSTNAME, port, backend_port)
    config_file = os.path.join(TMP_FOLDER, 'sqs.%s.conf' % short_uid())
    TMP_FILES.append(config_file)
    save_file(config_file, config_params)
    # start process
    cmd = ('java -Dconfig.file=%s -Xmx%s -jar %s/elasticmq-server.jar' % (
        config_file, MAX_HEAP_SIZE, INSTALL_DIR_ELASTICMQ))
    print('Starting mock SQS (%s port %s)...' % (get_service_protocol(), port))
    start_proxy_for_service('sqs', port, backend_port, update_listener)
    return do_run(cmd, asynchronous)

def exec_lambda_code(script, handler_function='handler', lambda_cwd=None, lambda_env=None):
    if lambda_cwd or lambda_env:
        exec_mutex.acquire()
        if lambda_cwd:
            previous_cwd = os.getcwd()
            os.chdir(lambda_cwd)
            sys.path = [lambda_cwd] + sys.path
        if lambda_env:
            previous_env = dict(os.environ)
            os.environ.update(lambda_env)
    # generate lambda file name
    lambda_id = 'l_%s' % short_uid()
    lambda_file = LAMBDA_SCRIPT_PATTERN.replace('*', lambda_id)
    save_file(lambda_file, script)
    # delete temporary .py and .pyc files on exit
    TMP_FILES.append(lambda_file)
    TMP_FILES.append('%sc' % lambda_file)
    try:
        handler_module = imp.load_source(lambda_id, lambda_file)
        module_vars = handler_module.__dict__
    except Exception as e:
        LOG.error('Unable to exec: %s %s' % (script, traceback.format_exc()))
        raise e
    finally:
        if lambda_cwd or lambda_env:
            if lambda_cwd:
                os.chdir(previous_cwd)
                sys.path.pop(0)
            if lambda_env:
                os.environ = previous_env

# WARNING: this means we're pointing lambda_cwd to a local path in the user's
        # file system! We must ensure that there is no data loss (i.e., we must *not* add
        # this folder to TMP_FILES or similar).
        return code['S3Key']

    # get file content
    zip_file_content = zip_file_content or get_zip_bytes(code)

    # Save the zip file to a temporary file that the lambda executors can reference
    code_sha_256 = base64.standard_b64encode(hashlib.sha256(zip_file_content).digest())
    lambda_details.get_version('$LATEST')['CodeSize'] = len(zip_file_content)
    lambda_details.get_version('$LATEST')['CodeSha256'] = code_sha_256.decode('utf-8')
    tmp_dir = '%s/zipfile.%s' % (config.TMP_FOLDER, short_uid())
    mkdir(tmp_dir)
    tmp_file = '%s/%s' % (tmp_dir, LAMBDA_ZIP_FILE_NAME)
    save_file(tmp_file, zip_file_content)
    TMP_FILES.append(tmp_dir)
    lambda_details.cwd = tmp_dir
    return tmp_dir