Function install_mesh_router 

pub fn install_mesh_router(
    router: &'static dyn MeshRouter,
) -> Result<(), &'static dyn MeshRouter>

Install this process’s mesh router, once; Err hands back the argument when one is already installed. Certified place-and-route installs its congestion-negotiating router this way, from its own side: the compiler never depends on it, so the published tree builds without it.