an class="pre">&lt;char&gt;</span></code>.  Use this to
match special regex characters, e.g. <code class="docutils literal notranslate"><span class="pre">\.</span></code> for a literal <code class="docutils literal notranslate"><span class="pre">.</span></code>
or <code class="docutils literal notranslate"><span class="pre">\\</span></code> for a literal backslash <code class="docutils literal notranslate"><span class="pre">\</span></code>.  Escaping a non-special
character is unnecessary but allowed, e.g. 