Function unity_re 

pub fn unity_re<P, E, V>(a: V, b: V, q: V, plan: &PolylogPlan<E>) -> V
where
    P: Policy,
    E: FloatElement,
    V: FloatVector<Element = E> + RealMathWithPolicy<Element = E>,

The real part of the unity series at mu = a + ib, including the fused or plain lead term. q = |mu|^2. See the module docs for the identities.