fn fuel_with_mass_required(mass: &Mass) -> Fuel {
    let fuel = fuel_required(mass);

    if fuel <= 0 {
        0
    } else {
        fuel + fuel_with_mass_required(&fuel)
    }
}
// Fuel required to launch with a specific mass when fuel itself got mass
Fuel required to launch with a specific mass when fuel itself got mass
Fuel required to launch with a specific mass when fuel itself got mass
fn fuel_with_mass_required(mass: &Mass) -> Fuel {
    let fuel = fuel_required(mass);
    if fuel <= 0 {
        0
    } else {
        fuel + fuel_with_mass_required(&fuel)
    }
}
fn fuel_with_mass_required ( mass : & Mass ) -> Fuel { let fuel = fuel_required ( mass ) ; if fuel <= 0 { 0 } else { fuel + fuel_with_mass_required ( & fuel ) } }
Fuel required to launch with a specific mass when fuel itself got mass
Fuel required to launch with a specific mass when fuel itself got mass
mass
&Mass
mass
&Mass