code: @Override public synchronized Long del(final String ... keys) {
          long deleted = 0L;
          String key;
          for (int idx = 0; idx < keys.length; idx += 1) {
              key = keys[idx];
              timers.remove(key);
              expirations.remove(key);
              for (IRedisCache cache : caches) {
                  if (cache.exists(key)) {
                      cache.remove(key);
                      keyModified(key);
                      deleted += 1L;
                      break;
                  }
              }
          }
          return deleted;
      }
docs: /* IRedisKeys implementations