# Set cURL callback
	private fun set_curl_callback(callback_receiver : CurlCallbacks) : CURLCode
	do
		var err

		if self.delegate != null then callback_receiver = self.delegate.as(not null)

		err = self.curl.native.register_callback_header(callback_receiver)
		if not err.is_ok then return err

		err = self.curl.native.register_callback_body(callback_receiver)
		if not err.is_ok then return err

		return err
	end