</code>
            transform to determine whether a function type <code class="computeroutput">R(A<sub>1</sub>,...A<sub>n</sub>)</code>
            is a <a class="link" href="../../CallableTransform.html" title="Concept CallableTransform">CallableTransform</a> or an <a class="link" href="../../ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a>.
            The former are evaluated using <code class="computeroutput"><a class="link" href="call.html" title="Struct template call">proto::