title: Generate a set of all possible records in TLA+
body: <p>Suppose</p>
  <pre><code>keyset == {&quot;k1&quot;, &quot;k2&quot;}
  valueset == {&quot;v1&quot;, &quot;v2&quot;}
  </code></pre>
  <p>I want to generate a set of all 4 possible record</p>
  <pre><code>{
    [k1 |-&gt; v1, k2 |-&gt; v1],
    [k1 |-&gt; v1, k2 |-&gt; v2],
    [k1 |-&gt; v2, k2 |-&gt; v1],
    [k1 |-&gt; v2, k2 |-&gt; v2]
  }
  </code></pre>