# poll method

E? poll()

Retrieves and removes the head of this queue.

Returns null if this queue is empty.

Example:

    final queue = LinkedQueue<String>();
    queue.offer('hello');
    final polled = queue.poll(); // 'hello'
    final empty = queue.poll(); // null

## Implementation

    E? poll() {
      if (_head == null) {
        return null;
      }

      final data = _head!.data;
      _removeNode(_head!);
      return data;
    }