code: @Override
    public <T> CASResponse cas(String key, long casId, T value,
        Transcoder<T> tc) {
      return cas(key, casId, 0, value, tc);
    }
docs: Perform a synchronous CAS operation.
  
  @param <T>
  @param key the key
  @param casId the CAS identifier (from a gets operation)
  @param value the new value
  @param tc the transcoder to serialize and unserialize the value
  @return a CASResponse
  @throws OperationTimeoutException if global operation timeout is exceeded
  @throws IllegalStateException in the rare circumstance where queue is too
  full to accept any more requests