pub fn list_value(&self) -> Option<(CellRef, CellRef)> {
        match self {
            SafasCell::List(car, cdr)   => Some((Arc::clone(car), Arc::clone(cdr))),
            _                           => None
        }
    }
///
/// If this is a list, returns the car and cdr cells
///
If this is a list, returns the car and cdr cells
If this is a list returns the car and cdr cells
pub fn list_value(&self) -> Option<(CellRef, CellRef)> {
        match self {
            SafasCell::List(car, cdr)   => Some((Arc::clone(car), Arc::clone(cdr))),
            _                           => None
        }
    }
pub fn list_value ( & self ) -> Option < ( CellRef , CellRef ) > { match self { SafasCell :: List ( car , cdr ) => Some ( ( Arc :: clone ( car ) , Arc :: clone ( cdr ) ) ) , _ => None } }
If this is a list, returns the car and cdr cells
If this is a list returns the car and cdr cells
&self
&self