pub async fn get_risk_free_rate(client: &Arc<FutuClient>) -> Result<String>Expand description
v1.4.98 T2-2 (mobile-source-audit Phase 2): 无风险利率 (期权定价).
调 daemon /api/risk-free-rate 等价 cmd 20231 GetRiskFreeRate. 返
HK/US/JP 3 市场无风险利率 (百分比 + raw uint64).