Function noncommuting_subsystem_exchange_phases 

pub fn noncommuting_subsystem_exchange_phases(
    local_dimensions: &[usize],
    retained_sites: &[usize],
    noncommuting_groups: &[NoncommutingGroup],
) -> Result<Vec<Complex64>>

General exchange phases induced by regrouping disjoint binary-mode groups.

Each inversion inside a group contributes that group’s unit-modulus phase. Distinct groups and sites outside all groups commute.