fn string(&self) -> String {
        let mut buf = "(".to_owned();
        buf += &self.operator[..];
        buf += &self.right.string();
        buf += ")";
        buf
    }
/// String - returns a string representation of the operator followed by it's expression to the right (-5) and satisfies our Node interface
returns a string representation of the operator followed by it's expression to the right (-5) and satisfies our Node interface
returns a string representation of the operator followed by it ' s expression to the right ( - 5 ) and satisfies our Node interface
fn string(&self) -> String {
        let mut buf = "(".to_owned();
        buf += &self.operator[..];
        buf += &self.right.string();
        buf += ")";
        buf
    }
fn string ( & self ) -> String { let mut buf = " " . to_owned ( ) ; buf += & self . operator [ .. ] ; buf += & self . right . string ( ) ; buf += " " ; buf }
String - returns a string representation of the operator followed by it's expression to the right (-5) and satisfies our Node interface
String - returns a string representation of the operator followed by it ' s expression to the right ( - 5 ) and satisfies our Node interface
&self
&self