DolphinDB HttpClient错误消息"url必须是字符串标量“

url = "http://example.com/api"
if not isinstance(url, str):
    raise ValueError("URL must be a string")

import re

def is_valid_url(url):
    regex = re.compile(
        r'^(?:http|ftp)s?://'  # http:// or https://
        r'(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?)|'  # domain...
        r'localhost|'  # localhost...
        r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})'  # ...or ip
        r'(?::\d+)?'  # optional port
        r'(?:/?|[/?]\S+)$', re.IGNORECASE)
    return re.match(regex, url) is not None

if not is_valid_url(url):
    raise ValueError("Invalid URL format")

from dolphindb import HttpClient

client = HttpClient()
response = client.get(url)
print(response)