Retrieves and removes the head of the queue represented by this deque
(in other words, the first element of this deque), or returns
{@code null} if this deque is empty.
<p>This method is equivalent to {@link #pollFirst()}.
@return the first element of this deque, or {@code null} if
this deque is empty
Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), or returns {@code null} if this deque is empty.
<p>This method is equivalent to {@link #pollFirst()}.
@return the first element of this deque, or {@code null} if this deque is empty