code: @Override
      public boolean containsValue(Object value) {
          if (fast) {
              return (map.containsValue(value));
          } else {
              synchronized (map) {
                  return (map.containsValue(value));
              }
          }
      }
docs: Return <code>true</code> if this map contains one or more keys mapping
  to the specified value.
  
  @param value the value to be searched for
  @return true if the map contains the value