&nbsp;&nbsp;&nbsp;&nbsp;(<span class="keywordsign">'</span>a&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;<span class="keywordsign">'</span>a&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;bool)&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;(<span class="keywordsign">'</span>b&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;<span class="keywordsign">'</span>b&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;bool)&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;<span class="keywordsign">'</span>a&