Function with_toml_env 

pub fn with_toml_env<'a, G, S, IT>(
    a: G,
    it: IT,
) -> Holder<'a, Holder<'a, Enver, G, String, &'a str>, Localizer<Value>, String, String>
where
    G: Getter<'a, &'a str>,
    S: AsRef<str>,
    IT: IntoIterator<Item = S>,