code: public T removeFirst() {
  		if (isEmpty()) {
  			return null;
  		}
  		T firstElement = elements[firstIndex];
  		elements[firstIndex] = null;
  		firstIndex = incrementIndex(firstIndex, 0);
  		return firstElement;
  	}
docs: Removes the first (inserted) element of the collection.
  
  @return Removed element or null if any