Function decode 

pub fn decode<T>(bases: &[T], digits: &[T]) -> Vec<T>
where
    T: Clone + NumAssignRef,

The value of each cell of bases.len() digits in digits, in the mixed radix of bases, as APL’s ⊥ gives it: Horner’s rule, with each step’s own base. The first base is never used. integer::decode gives i64s, checked for overflow.