如何使用Boto3只返回一个级别的键？

import boto3

# 创建Boto3客户端
client = boto3.client('s3')

# 执行查询并只返回一个级别的键
response = client.select_object_content(
    Bucket='your-bucket-name',
    Key='your-object-key',
    ExpressionType='SQL',
    Expression="SELECT your_key FROM S3Object",
    InputSerialization={
        'CSV': {
            'FileHeaderInfo': 'USE',
            'RecordDelimiter': '\n',
            'FieldDelimiter': ','
        }
    },
    OutputSerialization={
        'CSV': {}
    }
)

# 处理查询结果
for event in response['Payload']:
    if 'Records' in event:
        # 解析并处理记录
        records = event['Records']['Payload'].decode('utf-8')
        print(records)
    elif 'Stats' in event:
        # 处理统计信息
        stats = event['Stats']['Details']
        print(stats)