pub fn lookup_keyword(s: &str) -> Option<Token> {
        use Token::*;

        match s {
            "true" => Some(True),
            "false" => Some(False),
            "nil" => Some(Nil),
            "fn" => Some(Fn),
            "let" => Some(Let),
            "if" => Some(If),
            "else" => Some(Else),
            "return" => Some(Return),
            _ => None,
        }
    }
/// Get the Token for the given keyword, if valid.
Get the Token for the given keyword, if valid.
Get the Token for the given keyword if valid .
pub fn lookup_keyword(s: &str) -> Option<Token> {
        use Token::*;
        match s {
            "true" => Some(True),
            "false" => Some(False),
            "nil" => Some(Nil),
            "fn" => Some(Fn),
            "let" => Some(Let),
            "if" => Some(If),
            "else" => Some(Else),
            "return" => Some(Return),
            _ => None,
        }
    }
pub fn lookup_keyword ( s : & str ) -> Option < Token > { use Token :: * ; match s { " " => Some ( True ) , " " => Some ( False ) , " " => Some ( Nil ) , " " => Some ( Fn ) , " " => Some ( Let ) , " " => Some ( If ) , " " => Some ( Else ) , " " => Some ( Return ) , _ => None , } }
Get the Token for the given keyword, if valid.
Get the Token for the given keyword if valid .
s
&str