#introspection {
  append: 'apple', 'banana', 'pear', 2px, 2, 2em, 4px, 'hello';
  content: list;
  content: string;
  content: number;
  content: number;
  content: px;
  content: ;
  content: false;
  content: true;
  content: true;
  content: false;
  content: true; }