pub fn peek(&self) -> Option<&T> {
        if self.is_empty() {
            return None;
        }

        Some(self.vals[self.last()].as_ref().unwrap())
    }
/// Get a reference to the first element of the queue,
/// without modifying the queue. Returns `None` if
/// empty.
Get a reference to the first element of the queue,
without modifying the queue. Returns `None` if
empty.
Get a reference to the first element of the queue without modifying the queue . Returns ` None ` if empty .
pub fn peek(&self) -> Option<&T> {
        if self.is_empty() {
            return None;
        }
        Some(self.vals[self.last()].as_ref().unwrap())
    }
pub fn peek ( & self ) -> Option < & T > { if self . is_empty ( ) { return None ; } Some ( self . vals [ self . last ( ) ] . as_ref ( ) . unwrap ( ) ) }
Get a reference to the first element of the queue,
without modifying the queue.
Get a reference to the first element of the queue without modifying the queue .
&self
&self