@Override
  public CASResponse cas(String key, long casId, int exp, Object value) {
    return cas(key, casId, exp, value, transcoder);
  }
Perform a synchronous CAS operation with the default transcoder.

@param key the key
@param casId the CAS identifier (from a gets operation)
@param exp the expiration of this object
@param value the new value
@return a CASResponse
@throws OperationTimeoutException if the global operation timeout is
          exceeded
@throws IllegalStateException in the rare circumstance where queue is too
          full to accept any more requests
src/main/java/net/spy/memcached/MemcachedClient.java