Function distance_oracle::distance_rule

pub(crate) fn distance_rule(
    received_certs: &FnvHashMap<IdtyIndex, Vec<IdtyIndex>>,
    referees: &FnvHashMap<IdtyIndex, u32>,
    depth: u32,
    idty: IdtyIndex
) -> Perbill

Returns the fraction nb_accessible_referees / nb_referees