code: public AbstractHtml getChildAt(final int index) {
  
          final Lock lock = sharedObject.getLock(ACCESS_OBJECT).readLock();
          try {
              lock.lock();
  
              return children.toArray(new AbstractHtml[children.size()])[index];
          } finally {
              lock.unlock();
          }
      }
docs: Gets the child at the specified position. An efficient way to get the
  child at particular position. If you want to get the child at 0th(zeroth)
  index then use {@code AbstractHtml#getFirstChild()} method instead of
  this method.
  
  @param index
  from this index the tag will be returned
  @return the child at the specified index.
  @since 3.0.1
  @author WFF