  A mixed Dirichlet-Neumann problem is regularized with a family of singularly
perturbed Neumann-Robin boundary problems, parametrized by $\varepsilon > 0$.
Using an asymptotic development by Gamma-convergence, the asymptotic behavior
of the solutions to the perturbed problems is studied as $\varepsilon \to 0^+$,
recovering classical results in the literature.
