e two trees with equal keys.</p>

<p>This strategy keeps track of the multiplicity of each key, and matches every element from one tree with 
at most a single element with an equal key from the other tree. If a key has different multiplicities in 
the two trees, duplicate elements above the lesser multiplicity will not be considered matching.</p>

                      </div>
                      <div class="declaration">
                        <h4>Declaration</h4>
                        <div class="lang