<a name="Intro"></a>
<h1>Introduction</h1>

This is a variant of step-16 with the only change that we are using the
MeshWorker framework with the pre-made LocalIntegrator helper classes instead
of assembling the face terms using FEInterfaceValues.

The details of this framework on how it is used in practice will be explained
as part of this tutorial program.

<h3>The testcase</h3>

The problem we solve here is the same as the one in step-12.
