1. @DomName('EXTDisjointTimerQuery.isQueryEXT')
  2. @DocsEditable()
  3. @Experimental()
bool isQueryExt(TimerQueryExt query)

Source 

@DomName('EXTDisjointTimerQuery.isQueryEXT')
@DocsEditable()
@Experimental() // untriaged
bool isQueryExt(TimerQueryExt query) =>
    _blink.BlinkEXTDisjointTimerQuery.instance
        .isQueryEXT_Callback_1_(this, query);