text: let tabChildElements;
  
  window.onload = function () {
      // tabChildElement = document.getElementsByClassName('context')[0].children
      tabChildElements = document.querySelectorAll(".context>div")
      for (let i = 0 ; i < tabChildElements.length ; i++) {
          if (i != 0) {
              tabChildElements[i].style.display = 'none'
          }
          document.querySelectorAll(".nav>a")[i].onclick = function() {
              for (let j = 0 ; j < tabChildElements.length ; j++) {
                  if (j != i) {
                      tabChildElements[j].style.display = 'none'
                  } else {
                      tabChildElements[j].style.display = 'block'
                  }
              }
          }
      }
  
  }
  
  