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Under utils/common.py, 

TIMESTAMP_FORMAT_MILLIS = '%Y-%m-%dT%H:%M:%S.%fZ'

The %f produces time with microseconds, for example: 2020-03-18T19:43:18.115783Z.


However, when interacting the AWS s3 and sns apis, I receive DateTimes like this:

2020-03-02T22:32:13.240Z
i.e. milliseconds. 

This seems like a simple change to the utils. TIMESTAMP_FORMAT_MILLIS is named as if it should be millis as well. This is seems like a simple change. Is there a reason it should be microseconds?
try:
        func_arn = aws_stack.fix_arn(func_arn)
        func_details = arn_to_lambda.get(func_arn)
        if not func_details:
            return not_found_error(msg='The resource specified in the request does not exist.')
        if not context:
            context = LambdaContext(func_details, version)
        result = LAMBDA_EXECUTOR.execute(func_arn, func_details, event, context=context,
            version=version, asynchronous=asynchronous, callback=callback)
    except Exception as e:
        return error_response('Error executing Lambda function %s: %s %s' % (func_arn, e, traceback.format_exc()))
    finally:
        if suppress_output:
            sys.stdout = stdout_
            sys.stderr = stderr_
    return result
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)
    
    lambda_id = 'l_%s' % short_uid()
    lambda_file = LAMBDA_SCRIPT_PATTERN.replace('*', lambda_id)
    save_file(lambda_file, script)