code: public boolean removeLastOccurrence(Object o) {
          if (o != null) {
              int mask = elements.length - 1;
              int i = (tail - 1) & mask;
              for (Object x; (x = elements[i]) != null; i = (i - 1) & mask) {
                  if (o.equals(x)) {
                      delete(i);
                      return true;
                  }
              }
          }
          return false;
      }
docs: Removes the last occurrence of the specified element in this
  deque (when traversing the deque from head to tail).
  If the deque does not contain the element, it is unchanged.
  More formally, removes the last element {@code e} such that
  {@code o.equals(e)} (if such an element exists).
  Returns {@code true} if this deque contained the specified element
  (or equivalently, if this deque changed as a result of the call).
  
  @param o element to be removed from this deque, if present
  @return {@code true} if the deque contained the specified element