ACME客户端是用于自动化管理和签发SSL证书的工具。以下是使用Python编写的ACME客户端实现示例代码：

import requests

def get_challenge():
    endpoint = 'http://example.com/acme/challenge'
    response = requests.get(endpoint)
    if response.status_code == 200:
        return response.json()['challenge']
    else:
        raise Exception('Failed to get challenge')

def activate_challenge(challenge):
    endpoint = 'http://example.com/acme/challenge'
    response = requests.post(endpoint, data=challenge)
    if response.status_code == 200:
        return response.json()['result']
    else:
        raise Exception('Failed to activate challenge')

challenge = get_challenge()
result = activate_challenge(challenge)
print(result)

以上代码演示了如何通过HTTP请求和JSON响应来获取并激活ACME挑战。通过修改'endpoint'变量，可以将其应用于任何支持ACME协议的服务器。