docs: def element_focused(self, id_):
      """
      Assert the element is focused.
      """
  
      try:
          elem = world.browser.find_element_by_id(id_)
      except NoSuchElementException:
          raise AssertionError("Element with ID '{}' not found.".format(id_))
  
      focused = world.browser.switch_to.active_element
  
      # Elements don't have __ne__ defined, cannot test for inequality
      if not elem == focused:
          raise AssertionError("Expected element to be focused.")