public boolean contains(T t) {
        return t != null
            && (v1 == null || v1.compareTo(t) <= 0)
            && (v2 == null || v2.compareTo(t) >= 0);
    }
Whether a value is contained in this range.
<p>
<pre><code>
// true
range(1, 3).contains(2)

// false
range(1, 3).contains(4)
</code></pre>
jOOL/src/main/java/org/jooq/lambda/tuple/Range.java