Function fra_rate 

pub(crate) fn fra_rate<R: Scalar>(
    fra: &ForwardRateAgreement,
    view: &PricingView<'_, R>,
) -> Result<R, PricingError>

The FRA’s contract rate: the published fixing once the fixing date has passed, or once it has printed on the fixing date itself, else the simple forward over the accrual on the projection curve.

A fixing dated the valuation day is read if the store holds it and projected if not — FixingsView::observe, the rule every coupon applies.