he direct shadow tree
  let shadow1 = control.attachShadow({mode: 'open'});
  let shadowChild = document.createElement('div');
  shadow1.appendChild(shadowChild);
  control.i.setValidity(flags, m, shadowChild);

  // An element in an nested shadow trees
  let shadow2 = shadowChild.attachShadow({mode: 'closed'});
  let nestedShadowChild = document.createElement('span');
  shadow2.appendChild(nestedShadowChild);
  control.i.setValidity(flags, m, nestedShadowChild);
}, '"anchor" argument of setValidity()');

t