static get observedAttributes() {
    return ["disabled", "loading", "src"]
  }
Contains a fragment of HTML which is updated based on navigation within
it (e.g. via links or form submissions).

@customElement turbo-frame
@example
  <turbo-frame id="messages">
    <a href="/messages/expanded">
      Show all expanded messages in this frame.
    </a>

    <form action="/messages">
      Show response from this form within this frame.
    </form>
  </turbo-frame>