 "erlang" "erlang"
;; =&gt;  "erlang" "haskell" "python")
</code></pre>
<h2><a href="#an-integer-or-nil" name="an-integer-or-nil"></a>An integer or nil</h2>
<pre><code class="clojure">(def int-or-nil (gen/one-of [gen/int (gen/return nil)]))
(gen/sample int-or-nil)
;; =&gt; (nil 0 -2 nil nil 3 nil nil 4 2)
</code></pre>
<h2><a href="#an-integer-90-of-the-time-nil-10-" name="an-integer-90-of-the-time-nil-10-"></a>An integer 90% of the time, nil 10%</h2>
<pre><code class="clojure">(def mostly-ints (gen/frequen