Function check 

pub fn check<'a, 'r, 'm, 'd, 'p, E, P: Provider<E>, W: Work>(
    credentials: &'a Complete<'r, 'm, 'd, 'p, E>,
    counters: &Paths<'_, 'm, 'd, 'p>,
    required: &TimestampRequirements<Node, DocumentId<'m, 'd>, (), Cades>,
    index: &Index<'_, 'm, 'd, W>,
    scope: &Scope<'_, 'm, 'd, '_>,
    provider: &P,
    operation: &Reader<'d>,
) -> Result<Report<'a, 'r, 'm, 'd, 'p, E>, Error<P::Error>>

Check the complete original credential scope, using actual format receipts and the shared exact-artifact index. A swallowed callback failure remains terminal; later provider success cannot turn it into an empty complete set.