docs: function simpleComponent(elementName, elementClass, elementClassToExtend) {
      elementClass = elementClass || {}
      elementClassToExtend = elementClassToExtend || HTMLElement
  
      elementClass.prototype = Object.create(elementClassToExtend.prototype)
      assign(elementClass.prototype, elementClass)
      elementClass.__template = template(elementName)
  
      if (elementClass.prototype.createdCallback) {
        elementClass.prototype.__originalCreatedCallback = elementClass.prototype.createdCallback
      }
  
      elementClass.prototype.createdCallback = function() {
        fill(this, elementClass.__template)
        if (elementClass.prototype.__originalCreatedCallback) {
          elementClass.prototype.__originalCreatedCallback.call(this)
        }
      }
  
      document.registerElement(elementName, elementClass)
    }