Function transient 

pub fn transient(u: &Unresolved, determinism: Option<Determinism>) -> bool

The computed party of causes (spec 033, 3.5.2) and whether retrying an unresolved request unchanged can succeed (3.6.4). The computed party of causes (spec 033, 3.5.2) and whether retrying an unresolved request unchanged can succeed (3.6.4). The computed party of causes (spec 033, 3.5.2) and whether retrying an unresolved request unchanged can succeed (3.6.4). Whether retrying the same request unchanged can succeed (3.6.4): only for backend_unavailable, deadline_exceeded, and invalid_backend_output from a backend whose determinism is not bitwise.