Function fra 

fn fra(
    name: &str,
    index_code: &str,
    calendar_center: &str,
    business_day_convention: BusinessDayConvention,
) -> FraTemplate

Builder for a forward-rate-agreement template. name doubles as the registry code; the index conventions (forward-curve name, accrual period, day-count) are resolved from the index registry by index_code, so the FRA pins the same forward curve as the index’s vanilla swap.