    expect(nextToken()).toBe <span class="hljs-string">'+'</span>
    expect(nextToken()).toBe <span class="hljs-string">'('</span>
    expect(nextToken()).toBe <span class="hljs-string">'b'</span>
    expect(nextToken()).toBe <span class="hljs-string">'+'</span>
    expect(nextToken()).toBe <span class="hljs-string">'c'</span>
    expect(nextToken()).toBe <span class="hljs-string">')'</span>
    expect(nextToken()).toBe <span class="hljs-literal">null</span>

  check <span class="hljs-string">"ok: c