quence operation</em></span>, and the function object passed to <code class="literal">for_each</code> should not modify its argument. 
The requirements for the arguments of <code class="literal">for_each</code> are unnecessary strict, since as long as the iterators are <span class="emphasis"><em>mutable</em></span>, <code class="literal">for_each</code> accepts a function object that can have side-effects on their argument.
Nevertheless, it is straightforward to provide another function template with the fu