Function crossover_with_paths 

pub fn crossover_with_paths(
    left: &Expr,
    right: &Expr,
    receiver_path: &ExprPath,
    donor_path: &ExprPath,
    seed: u64,
    ordinal: u64,
    limits: &Limits,
) -> (Expr, Provenance)

Deterministic exact-path crossover, primarily for auditable replay and tests.