ConcurrentDeque: a test task for KTor summer internship
The implementation is straightforward. The deque uses a doubly-linked list to keep all elements. Thus, all operations
(except contains) will run in O(1) time complexity.
Synchronization is achieved due to using @Synchronized annotation on every method of the deque. This is the slowest, yet very
reliable solution, because it's guaranteed that the deque will never be in inconsistent state, because it is always
automatically being locked by mutex on every operation.