s literal notranslate"><span class="pre">+</span></code> and <code class="docutils literal notranslate"><span class="pre">?</span></code> have higher precedence than concatenation.  <code class="docutils literal notranslate"><span class="pre">|</span></code>
has lower precedence than concatenation.  This means that the regular
expression <code class="docutils literal notranslate"><span class="pre">^ab+d$</span></code> matches <code class="docutils literal notranslate"><span class="pre">abbd</span></code> bu