         makeUniqueWithCapacity(grow(count + 1))
         buffer.append(newElement)
     }
-    
+
     /// Append `newElements` to the end of this queue.
     public mutating func appendContentsOf<S: Sequence where S.Iterator.Element == Element>(newElements: S) {
         makeUniqueWithCapacity(self.count + newElements.underestimatedCount)

        self.start = i
        self.count += 1
    }
    
    internal func popFirst() -> Element? {
        guard count > 0 else { return nil }
        let first = elements.advanced(by: start).move()

        }
        p.deallocateCapacity(capacity)
    }

    @warn_unused_result
    internal func realloc(capacity: Int) -> DequeBuffer {
        if capacity <= self.capacity { return self }
