Function push

code/new-context-api/public/app.js:11962–11972

(cursor, value, fiber)

  }

  function push(cursor, value, fiber) {
    index++;

    valueStack[index] = cursor.current;

    {
      fiberStack[index] = fiber;
    }

    cursor.current = value;
  }

  function checkThatStackIsEmpty() {
    {