# peek method

E? peek()

Retrieves, but does not remove, the head of this queue.

Returns null if this queue is empty.

Example:

    final queue = Queue<int>();
    queue.offer(100);
    print(queue.peek()); // 100
    print(queue.length); // 1 (element still in queue)

## Implementation

    E? peek() {
      if (_elements.isEmpty) {
        return null;
      }
      return _elements.first;
    }