docs: function elSetState(el, state, highlightDigit) {
      if (el) {
          el.trigger(state, highlightDigit);
          if (el.isGroup
              // Simple optimize.
              && !graphicUtil.isHighDownDispatcher(el)
          ) {
              for (var i = 0, len = el.childCount(); i < len; i++) {
                  elSetState(el.childAt(i), state, highlightDigit);
              }
          }
      }
  }