fn perp_current_value(
perp: &PortfolioMarginPerpExposure,
spot_price: f64,
underlying: &str,
) -> Result<f64, MarginError>fn perp_current_value(
perp: &PortfolioMarginPerpExposure,
spot_price: f64,
underlying: &str,
) -> Result<f64, MarginError>