Collection addAll removeAll returns boolean
<p>C is a collection of type <code>Set&lt;T&gt;</code>, F(x) returns an collection of Set, what i want to do is to perform operations between sets like union, intersection, difference</p>

<pre><code>// C union ( F(X) \ F(Y))
C.addAll( F(X).removeAll( F(Y)))); //error boolean because removeAll returns a boolean
</code></pre>

<p>alternative i could</p>

<pre><code>C_aux = new HashSet&lt;T&gt; ( F(X));
C_aux.removeAll( F(Y)); 
C.addAll( C_aux);
</code></pre>

<p>anyway to do this without declaring the auxiliar collection ? (skip/ignore the boolean return)</p>
