pub fn with_vars<K, V, F, R>(kvs: impl AsRef<[(K, Option<V>)]>, closure: F) -> Rwhere K: AsRef<OsStr> + Clone + Eq + Hash, V: AsRef<OsStr> + Clone, F: FnOnce() -> R,
Sets environment variables for the duration of the closure.
The previous values are restored when the closure completes or panics, before unwinding the panic.
value is set to
None, then the environment variable is unset.
If the variable with the same name is set multiple times, the last one wins.