fn resolve_env_variable(s: String) -> String {
    if s.starts_with('$') {
        env::var(&s[1..]).unwrap_or(s)
    } else {
        s
    }
}
/// If s starts by a '$', replace it by the environment variable of the same name
If s starts by a '$', replace it by the environment variable of the same name
If s starts by a ' $ ' replace it by the environment variable of the same name
fn resolve_env_variable(s: String) -> String {
    if s.starts_with('$') {
        env::var(&s[1..]).unwrap_or(s)
    } else {
        s
    }
}
fn resolve_env_variable ( s : String ) -> String { if s . starts_with ( '$' ) { env :: var ( & s [ 1 .. ] ) . unwrap_or ( s ) } else { s } }
If s starts by a '$', replace it by the environment variable of the same name
If s starts by a ' $ ' replace it by the environment variable of the same name
s
String
s
String