pub fn is_nil(&self) -> bool {
        match self {
            SafasCell::Nil  => true,
            _               => false
        }
    }
///
/// Returns true if this cell is nil
///
Returns true if this cell is nil
Returns true if this cell is nil
pub fn is_nil(&self) -> bool {
        match self {
            SafasCell::Nil  => true,
            _               => false
        }
    }
pub fn is_nil ( & self ) -> bool { match self { SafasCell :: Nil => true , _ => false } }
Returns true if this cell is nil
Returns true if this cell is nil
&self
&self