In reviewing this __init__ method, I noticed a potential improvement in the way URL validation is handled. The current approach checks base_url.split("/")[0] against "http:" and "https:", which can lead to incorrect results if the URL contains unexpected formatting or additional whitespace. A more robust approach would be to use Python’s urllib.parse module to properly parse and validate the scheme, ensuring the code works reliably for different URL formats. Additionally, it would be beneficial to add more descriptive docstrings explaining each parameter, especially convert_datetimes_to_utc and http_proxy, so that future maintainers understand their purpose and default behavior. Finally, initializing self.server to None is fine, but it might be worth documenting why it is deferred rather than set during initialization, to avoid confusion for other developers working with this class.