cond. Because of the many character classes used in
regular expressions, it is common to use a raw string here, unless string
interpolation is required.</p>
    </section>
    
    <section class="summary source-code" id="source">
      <h2><span>Implementation</span></h2>
      <pre class="language-dart"><code class="language-dart">external factory RegExp(String source,
    {bool multiLine = false,
    bool caseSensitive = true,
    @Since(&quot;2.4&quot;) bool unicode = false,
    @Since(&quot;2.4&quot;) 