text: var maindiv = document.querySelectorAll('one-evm-unit'); 
  var unit = maindiv.children;
  
  var currentLed = 0;
  function a(id) {
      var button = document.getElementById(id);
      parent = button.parentNode.parentNode;
      var children = parent.children;
      var childId = children[1].id;
      console.log(childId);
      led = document.getElementById(childId);
      if (typeof led !== "undefined") {
          led.style.display = "block";
          hide(led);
      }
  }
  
  function hide(led) {
      setTimeout(function(){
          led.style.display = 'none';
      },2500);
      
  }
  